340 Max HP Potential with X/J heads?

You just tap and plug, drill overlapping on that plug, tap and plug . 2 plugs overlapped for heat cracks between cylinders.

Anything can be repaired sure.... I am just thinking in practicality.... This summer we scorched a head on a grudge car I help with. Head was fixed no problem and no issues since....

The other thing that I think about is getting someone with porting knowledge to actually work a set of cast-iron heads these days. I have no idea as to if this is even a consideration but working with aluminum is easier and safer...

JW