You could machine the blocks lifter bores with a little bit of offset, but the Lifter's roller still needs to be on the cam lobe. So I don't think you'll see anyone changing their location. The reason for doing any of these things is to get overall valve train weight down and the pushrod further away from intake ports so the intake runner is bigger. The overall diameter might be something to look at .873, .903 diameter and maybe some others may still fit on the same 1.818? "Pontiac" center to center distance. I'm going to go look and see what most of the fancy keys are using for bushings and diameters. Might be something that Bob and Frank will consider or something that can be done with BHJ cam tru stuff here at
www.ictcengines.com in the future.
The important thing right now is to have a simple roller lifter kit part number that will drop in. That's going to be a .842 diameter with enough height to get the link bars off the block using any base circle cam through a manufaturer lifter kit part number Or temporarly buy a BBC or SBC kit and the Pontiac link bars.
-Rob