I will be glad to share my experience.
1 thing. I was using stock magnum heads. We cut the seats for 1.97 RT valves and I had Hughes .500 lift Single springs with 2.2 retainers. I was using a Hughes custom hydraulic cam with a .300 base circle. When all said and done I was at about .480 lift. I was racing oval dirt 1/4 mile where the rules said factory only on the valve train except screw in studs and guide plates were allowed. I used 3/8 MP fulcrums that I cut 1/2 the platform off with a hi speed cutting wheel on a die grinder. I used the 5/16 x 3 8 studs from the Comp Cams kit along with the guide plates. I used the MP push-rods made for the conversion. (7.165 I think was the length)? I also had to take some material off the stud close to the bottom because the fulcrum would go down to far and get tight. I then used Stock rockers with poly locks and the the adjustment was 1/2 turn from zero lash. I ran this set up for 15-20 race nights at 6500 RPM lap after lap. I broke a fulcrum in half but never noticed a running difference. We found it doing a manifold swap when the rules changed for the next year..
The along with "any factory" manifold rule change it was also changed that "stock style" rockers could be used. I then went to a custom length hardened push-rod and the Summit Brand 1.6 Chevy rocker. At that time I began to converse with Joey Case from Dallas GA. He advised me to run the lifters preloaded at .120 deep.
I never had a geometry problem that was out of this world.
