Even with the new design main bearings, it's a definite possibility that you might need to use shims to establish the correct oil clearance. Unless your machinist is willing to do a line bore job with four different bearing bore diameters, (most won't even attempt it) shimming for the right oil clearance is almost a "must do" situation. One main bearing on John's 261 needed a single shim to correct the clearance, and it was machined for the later model bearings.
BTW- - - -I've got the line bore tooling and I know how to handle that little chore, but I'm older than dirt!
Jerry
