It went flat. That cam may like 9:1 compression. What stall are you using? A mild cam will tolerate stock pushrods even if the geomtry is not exact. You can check it with a length checking adjustable pushrod. The installed height is for rated seat pressure, as long as you have open clearance it should be fine.
My 305 c10 worked well with a performer cam, 906 vortec heads , performer intake, AVS 650, 3.73 gears, 3000 stall , 28" tire, headers, msd ignition. It is a heavy truck and cannot sacrifice low end. Save for a supercharger 6 psi is worth ever penny.
Do a search on engine break in. Make sure to prime the engine oil system while turning crank by hand. Look for oil at all rockers.