That'd be a hoot with my current build (451 with a Mini-Express .654" mushroom cam). But don't the port walls get awfully thin in places? How do they hold up in the long run for cracking?
I think if I were going to spend that much on porting I'd start with a good aluminum head though ;)
It makes no sense at all to do that much work to factory iron heads unless class rules say you have to use an iron head or you just have to use an iron head for some personal satisfaction.
As to cracking, you gotta be smarter than your cylinder heads. We've used one pair of 906 heads flowing 340cfm on three different engines. Even when Comp Cams forgot to turn the water into our engine when it was on their dyno and the engine ran so hot the paint was burning off the cylinder heads, they didn't crack.