Suggestion. Send a picture of the pushrod ends and line all the them up together to compare their length.
Roll a pushrod on a flat surface to quickly check for bent ones.

Attached is a picture of the water jacket access points that I was talking about.
Freeze plugs can be removed by drilling a hole in the middle and using a screwdriver to twist them out.
It may be difficult for you to do this step so save it for last resorts.
Attachments
Access points.jpg (89.12 KB, 154 downloads)


"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."