I am not old enough to look at the pictures, but I do remember something that may pertain to these motors, maybe not-
Bob Kaiser (Systems boat) worked with GM on a hi-tech marine engine. If I remember correctly, it was 3?? cubic inches and was turboed. The heads and block had seperate cooling sytems- They built a few prototypes and had problems because they used a prototype Vette ECM that had a flaw in the mapping which caused a lean condition. I think one block cracked through a main bearing bulkhead. There was an article about this about 6 years ago, I don't know if kept the magazine.