You must be the "talk about it" type.
I do it... and I do it looking bone stock.
If you dont get it, if not interested... then move to another thread about aluminum heads.
Justin knows what he is doing, is a long time racer, his stuff runs excellent, and he is a very valued poster.
He is 100% correct. Putting a tiny iron head on a 4 inch arm motor is like wearing a life jacket in ankle deep water.
Even a well done eddie head is WAY to small to support a long armed 420 inch motor. I had such a motor and it was weezing at 1100-1200 foot mark.
For that matter, even a W2/5 head is marginal for a 420 inch motor. Even they were designed long before the advent of 4+ inch cranks. Been there done that too with a 422 W5 deal thats been 140 mph at 3200 on leafs.
Your barking way up the wrong tree here. Justin knows exactly what he is talking about and is 100% on the mark.
Can you do it. Yes. Is it a tractor. Absolutely