Update:
I took all your advice and did what I had to do: drilled two vista concert toms and a kick for l-arm/leg mounts on the former and modern spurs on the latter. I went quite slowly with a brad point bit and had no issues except for slight chipping on the exit side of one or two of the holes. Then I used a countersink to add an bevel to the edges. Even went back and used a round file to widen the holes a little so the hardware wasn't too snug (and beveled again). Added a layer of neoprene between metal and acrylic, and voila.
Funny enough, when I removed the original tom mount from the kick to replace it with a new one, I saw how rough a drilling job was done at the factory. Must have been a Friday :P