The old Chrysler Power magazine, November 1991 issue had a pretty good article on porting small block heads.
It would have been a better article with more proof reading as it has several typos in it where the side chart has some differences that does not match the data in the article?
I think the most interesting part was the exhaust flow did not respond too much to porting, but did respond well to using an exhaust valve with a tulip style head?
They also found filling the intake floor helped velocity while not hurting flow, so no need to take metal away from the port floor.
As expected most gains were in porting the bowls, and valve job. I think they back cut the intake valves too.