OP says he has a billet block. Not sure what he means by that since the only billet blocks I'm aware of are Top Fuel type blocks. But if what he is saying is correct then the lifters bores would've been machined on a CNC rather than cast. So unless the CNC program was defective, the lifter bores should be in the correct location. Worth checking of course but a billet block shouldn't need bushings. My guess is that billet blocks already come with bushed lifter bores since the guys who buy billet blocks use 0.937 or 1 inch lifters. OP should measure his block first to see what size the lifter bores are since billet blocks tend to be custom made and the lifter bores are most likely not 0.904 diameter.