All the Aussie Pro Stock stuff has a billet head, Slawko or VED from what I've seen. The cast stuff from the early days would crack in the intake bowl from what I've been told. Mopar did a revision and called it the P9, I think aimed more so at the dirt track Midget 4 cylinder racing. Brett Miller had a set a while ago for something, no idea what came of that project.

There are some guys running the cast heads on some Super Stock cars. Elite Motorsport have done a few 358 cube engines that made a lot of power. Bob Book has done several of the 400 cube versions for Aussie P/S.
Main issue is getting blocks, a lot of the R4 stuff that is getting raced with these engines has 8 sleeves and an almost complete fill on the block.

Marshall Pearcy is still racing one in his Challenger, I think that has a large single turbo on it now? Hopefully he chimes in.

They're not at all a cheap exercise, and the very limited number of blocks available makes it even worse, that and most people don't want to build 2.8-3hp N/A engines