Missed on this combo?

moper said
A mentor of mine was one of those messing (and winning) with the 351C heads. Iron inserts welded in and the port was reshaped.

Iron - For what it's worth I agree with your guy.

Back in the day, the one and only on i saw hand half of the exh port cut off then a alu piece was bolted on to fix the exh problem.
Was told that it work GREAT! but was a ***** to keep coolant leak out of the equation.