I'd start looking for a D9 block if you don't already have one. The cylinders are better suited for a stroker. Not 100% necessary but I'd hold out for one. What stroke & compression you are using will give a better idea on what iron head you can use if you are not going to buy a set of aluminum heads. By the time you prep a set of iron heads you would probably be better off just buying a set of aluminum heads. Figuring you would have to buy bigger valves, get all the machine work done, cc & mill, cut for spring seat cups, guides trimmed down, cut for PC seals, possibly some work done on the rocker stands to run a full roller rocker & hours of porting and polishing it all adds up quickly.