Hemi cast iron heads are going to make a lot more power than any stock BB cast iron heads. If you look around a bit you might find a set of Indy -1 cast iron heads. If you can find the iron -1 heads then it would be cheaper to build a wedge and it would probably make just as much power.

Another option is to find some older cast heads from a NHRA super stock guy. Heads that are no longer competitive in SS might work just fine for a puller engine. Might need a sheet metal intake though to work with the heads since they move the ports around in those things.

Big bore and short stroke will make the most power. Then you'll have to sort out the gear ratios to make it pull hard.

Good luck either way.