Hydraulic Roller Lifters w/LA Block?

I had the same problem with a pre magnum 360LA roller block with magnum roller lifters and a .548 lift hyd roller cam. After a lot of measuring and consulting with the tech at comp cams the cam was ground on a .900 base circle to keep the lifters in the bores(this was before retro fit hyd roller lifters) this engine ran great and was regularly shifted at 6700 rpm. The tech told me at the time that the .900 base circle was used on small block chevy 383 strokers so the cam would clear the rotating connecting rods. At this point of your build I think the small base circle cam is the least expensive way out.