I bought an old LP Studio with a Kahler on it. I took the Kahler off to put a TOM bridge back on. I had assumed (wrongly) that flat mount meant no routing, and was pretty horrified when I saw the gaping hole where the Kahler was. So my questions are- any tips on filling the hole back in? Is it worth the effort or even possible to try to match the grain with a filler block? I'm pretty good in a woodshop but I'm no luthier, so I might just take it in. Also, the tailpiece studs on the Kahler don't look stock. Will those have to be changed to fit a TOM?

Ha you're screwed. I'd leave the Kahler in bro, it would be too much work to fix a hole like that. You could try building a Les Paul to put your Tune-o-matic in though
I'm FAT!
Haha yeah that's not exactly the solution I'm looking for. The kahler is coming out, I can't stand the thing. I hate having to carry 4 allen wrenches everywhere and I hate having to chose between bent or whammy-ed notes being in tune
I did think a little bit about putting some kind of electronics in the hole, like a tuner or something. Not gonna do that though because it would look stupid
Hmm.... yeah that's not a bad idea. Do you know if they make one that uses the same posts as the trem version?