Nah, there's no panacea here. You _could_ fill the hole in with JB Weld, which is as close as you can come to what you're asking for, but that'll really do exactly zero good here. The only real solution is to weld in the hole, grind the weld flat, and then re-drill.
I would do two things:
1. Tap your holes, add bolts, and run the existing triple tree just the way it is.
2. Buy a new triple tree, and do the drilling and tapping on it while it's off the bike, and then only install it if you are successful.
This gets you the maximum road time. The existing tree will probably be just fine like that, the steering stops take very little force in normal operation, so just avoid high-speed tank slappers and it'll be fine. You'll find it much easier to do the mod on the new tree when it's not on the bike.
The hardest part about swapping the lower triple tree will be replacing the bearings and dealing with the wiring. Aside from that, since you were planning on replacing the fork seals anyway, it's only a little bit of disassembly past dropping the forks out, to swap out the lower tree.
mystic_1