I wouldn’t put a dime into a cast iron head if I wasn’t required to. I’m at touch over 400 with my highly ported x heads. If the cast head needs work, save up and go aluminum. Repairable/lighter/better casting/easier to get ported. Rebuilding a set of cast heads isn’t really financially smart. As to the Eddy head, I have a set that have not given me any issues. Two issues that might need addressing. Alternator figment and if you use the 340 exhaust manifolds. They might hit the head. Not hard issues to solve, just need to keep them in mind.