Kisner The holes for the script are 7/64 " as for the pony start with the same an do a test fit (b-4 you paint) if not than go up to the 1/8 " bit. But remember they are supposed to be a "very snug" fit so be careful and use slow even pressure . We dont wanna scratch that new paint
Always insert the the snap nuts into the holes first (I pushed them in with a pencil eraser ), then put a drop of lube on the pegs and in they go. Hope this helps