You did not say you primed the lifters or not.
How long has the engine been running?
H.V. oil pump is a no no. Causes premature wear on camshaft drive for the distributer & wears out the distributer gear.

I have seen lifters not pump up for a while,even when engine has been running for a while.
Are the lifters noisy?

MBHD


12 port SDS EFI