Put a new Isky or Howards cam and lifters in it.
This time break it in using old stock OEM SBC springs installed
at max installed height (1.75"+ no shims)
Then install the high perf springs.
make sure the spring seat pressure does not exceed 115#
and the open pressure does not exceed 330#
It pays to get the details right.
The moly slip E supplement works great.
Use motor oil that is not off the shelf
passenger car oil.
Many of the "Racing" labeled oils still have a good bit of zinc.