In 1970 I had a tune-o-matic bridge installed on a 1965 SG Special. Back then, it was just an old guitar, no one worried about keeping it original in those days, and truthfully, it sounded better with the TOM, and stayed in tune better.
But I couldn’t afford to have it refinished, so the tech simply glued some mahogany dowels in the holes where the old Gibson one piece bridge was, and stained the ends to match the cherry finish. The guitar is still around, and still looks every bit as homely as it did in 1970. I just didn’t care how a guitar looked back then.
Obviously, any value compared to an un-modded one is minimal. But I got an awful lot of use out of that thing; at least, that’s my excuse for destroying its value!