ithacaartist
Repairing the gun would make it functional... it would still be a "putzed with" gun, and the value would be less than one whose frame did not require repair. IF the gun is going to be shot, I would have it repaired... and restored. The problem with the repair is that because of the differences in the steel, the blueing would not be perfect, but would blue differently for each type of steel (original, versus the welding rod)...
If it were my gun, and had a friend who do what you say you can, I would definitely fix it. It is probably worth more as a restored shooter, than as original with a butchered front grip strap.
To receive this gun for repair, you would either have to meet face to face with the owner, and he would have to stay with you as you accomplished the repairs, OR...
If you are a C&R license holder or FFL License holder, you can receive it yourself in interstate shipping.
If you aren't a license holder, then you will have to enlist the services of a license holder for shipping purposes and there is usually a charge for that above the price for the shipping.
If this is one time thing on repairing a firearm. The owner could sell it to you... you could fix it because it is your own gun, then after it is fixed, you could sell it back to him. But you still have to deal with all the licensing and shipping issues mentioned above...
If I were the seller, I would definitely plan a trip to your house to watch you work on it.
The easiest and most legal way to accomplish the task.