Max, Thanks for the post, and Glen thanks for your excellent overview of what's involved reworking an engine for true reverse flow. I think that there are lots of people (I was one) that are a little bit confused about reverse flow cooling due to the different water pumps out there for the older engines that are tagged "reverse flow" when they are really "reverse rotation" to account for the serpentine belt. For those, like on my SBF, the "reverse flow" pump flows the same as the "regular flow" pump, but the impeller is curved the other way for reverse rotation.
I've read some about Smokey Yunick's super efficient engines, mostly back when he was doing things and had articles in Popular Science, but I think I may dig a bit deeper into his history. He was a brilliant guy.