small block heads, 4027596 casting # any good??

If it were me, I'd spend the cash to get a quality performance (5 angle) valve job and replace what needs replacing. Dont sweat porting at all. With the same prep, alls casting large port LA heads start around the same place... 215-225 cfm on the intake side. You eat up a lot of cash quickly on porting, and if the guy doing it isnt really good, a lot of that cash is just wasted. The first few hundred make the most difference.