74 Swinger Project
Sorry to hear. It took almost 6-7 months of "Gremlins" for mine. Hang in there it's worth it.
What radiator are you running?
Stuck lifter on a fresh rebuild? How long did it sit before you started it up? If it is a stuck lifter I would put a bottle of marvel mystery oil in the engine oil and let it run for at least 15 minutes.
Then change the oil and filter.