I pulled the shafts and rockers yesterday to see if there was anything weird happening and it looked OK to me. The 383 magnum was a low-mile engine and the shafts were still in really good shape.

I thought .08 was an excessive amount of preload as well but thats what the Hughes cam instructions said to use.

I set preload by rotating the engine, setting intake when exhaust was opening and exhaust when intake was closing. I turned the pushrods with my finger and slowly tightened the adjusters until i felt resistance, then tightened 2.5 turns for .08 the first time and 1.25 turns for .04 the second.