Certainly that can be fixed. You can simply hone on a very coarse stone, freshly lapped, until it passes the sharpie test. You will be removing quite a bit of steel obviously, so you should check the bevel angle first and decide if you should tape the spine or not.
To mesure the bevel angle, first hone the razor until you have a good bevel on at least the toe or heel. You should be able to see the contact area on the spine. From the back edge of the spine's contact area or bevel flat, measure to the razor's edge. Do this at a point along the blade where you have a bevel. Be accurate. Use a dial caliper or vernier scale. Next, at that same point, measure the thickness of the spine. The first measurement is the hypotenuse of a right triangle, with the right angle inaccessible inside the spine. The acute angle is half of the bevel angle. Half of the spine thickness is the opposite side. Now you can simply use those two figures to calculate half the bevel angle, double it and you have your bevel angle.
Next measure the hypotenuse at the deepest part of the frown. This tells you what the bevel angle will be after you have straightened out the edge, if you were to tape the spine. If it comes out under 17 degrees, then consider taping the spine. More likely, just eyeballing it I would guess it will be around 18 degrees, which is a little on the obtuse side. So, since you are taking so much steel from the edge and reducing blade width so much, you need to see at least some reduction of the spine thickness, and so taping should not be done, or at least not the whole time you are honing out the frown. Use your dial caliper and your calculator to guide you, and try to end up with a bevel between 16 and 17 degrees for the probable best shave from the blade.
If you end up with a wide bevel flat on the spine, you can always sand down the edges of it and re-round the spine. It's not a big deal. If it is VERY wide, then you should do so, not for cosmetic reasons but to reduce the contact area of the spine so that normal honing wears spine and edge proportionally thus preserving the bevel angle for generations to come.
But back to the frown itself. It is a good idea to hone the frown out on a honing surface that is wide enough to accept the entire edge, and freshly lapped flat. You aren't going to do a good job straightening out the edge on a humpbacked stone or one that forces you to x-stroke. Your eyeball is no good judge of flatness. Lap that rock. If it is already flat, the grid will be gone after just a couple dozen laps anyway. Definitely start out very coarse. No sense diddling around with a 1k stone for several hours. When the frown is nearly gone, you can progress upward toward your regular bevel setter so you are not still dealing with deep, coarse scratches after your edge is straight. I use sandpaper for this operation. I glue 1/3 sheet (long way) of sandpaper to a polished marble tile, either a 12x12 or a 4x12 edge tile. The 11" long piece of sandpaper carefully applied with a very very light application of spray adhesive gives a nice flat surface. You can also use a very heavy piece of glass, or a calibrated granite lapping plate, or the sink cutout from a polished granite counter top. All of these surfaces should be flat enough. For a frown that deep I go with the big guns, grit wise. I would start with maybe 60 grit. It will help initially to hone with the spine leading for the first few dozen laps. Anyway, remember to stop with the coarsest grit when the frown is nearly gone and begin a progression, ending with 1k grit or finer. There. Edge is straight, bevel is set, and if you were watching your bevel angle and adjusting pressure toward edge or spine, and taping IF NECESSARY, you have a good shaving bevel angle. Now you can sand your spine back round if necessary, and continue the honing progression. You could also take this opportunity to sand and polish the blade if desired but you don't really need that on that blade. Continue your progression to your finishing stone or finishing film, strop, and shave.
There was a time when I would have said, "Breadknife it", but I often found that the bevel angle had been made undesireably obtuse, requiring thinning of the spine. So, says I, why not just hone that rascal normally from the start? The only good reason I now see for breadknifing is if you do not have a stone wide enough and coarse enough to hone the razor flat and straight. And with sandpaper and flat surfaces available for it, there is no reason to limit yourself to your stones if they are inadequate. Breadknifing would be a good tool if the bevel angle was too acute, though. YMMV.
No matter how you do it, it will probably shave. Lots of guys are blissfully ignorant of blade geometry and most of their razors will shave a face. Some better than others of course. For the best and most consistent results, though, shoot for a proper bevel angle, especially when you are doing a major repair and removing a lot of steel. An ordinary honing, if it shaved before, then it should shave when you are done. A small repair might affect the geometry a measurable amount but an amount that will go more or less unnoticed in the shave. A big job where you are taking off 1/8" or more of steel will make a difference in the shave if you let it do so.
Now... you say this will be your first honing. Well, you can do it yourself but you would be better off putting it aside for now. Your first try at honing should be a simple touchup of a previously sharp razor that you have simply shaved with to the point where it no longer shaves well. A touchup only requires the use of your finishing stone or maybe 1u lapping film. After getting good results with your touchups, try your hand at setting the bevel of a razor in good shape, running your progression, and finishing. When you are getting good edges without backtracking, then it will be time to do some edge repair work. Try a few minor chips first. Then tackle your frownie. You will be glad you waited.
Send it out? Yeah maybe. But make sure it will be done properly. Or at least make sure it will be done to your specifications. But I think you ought to put it aside and do it yourself, when you are ready for it.
"A noble heart embiggens the smallest man." (Jebediah Springfield)