If all you did was install a new cylinder head, then I would be removing the cam cover and inspecting. It's possible a cam follower got out of position, and can be pushed back in place.
Back when, the Lima came with 'hairsprings' or grasshopper springs to keep tension on the followers so they did not fall out of place. They quit that after a few seasons.
Other than that, it sounds like a collapsed lifter that is not pumping up. They can become jammed if fully compressed, and oil pressure may not be enough to expand them to normal size.
If that was the case, you have two choices: remove & replace a lifter that doesn't lift or remove, disassemble and un-jam the lifter/support, and replace.
If you run the engine with the cover off, you will rust-proof your engine compartment. A hurricane of oil will fling everywhere.
Start at the front and feel the followers for one or more that are floppy loose. They should not be that loose. Be careful as the machined edges will cut the snot out of your fingers if you are not. Remove the follower and pull the lifter support. Fiddle. Return, re-cover and start. It may clank or rap for a minute after startup, but should shut up within a few minutes at the outside.
One other alternative is to take it on the highway and run the rpms up so oil pressure is at a max. You do not want to do it sitting still as you'll cringe at the noise.
tom
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