Ls cranks are about .90 shorter in length than a G3 hemi crank.
What does the rear main seal look like? what is the main journal dia? and is the tone wheel sensor hole drilled?

Back when you had PM me about the 2 blocks, (when I was looking to build a destroked g3), I contacted one of engineers I know at Mac ,His impression was the block was designed to use the R5 cranks......I'm skeptical of that because of the difference in the rear main seal and no tone wheel attachment. He also said that Mac had Valve gear for it but sold the patterns and CNC programs. he also said there was a SB2 type Victor manifold for the project.

Yes it was designed to use in a Trans am style race series with a 5.0L limit, but when DCX fell apart the program was scrapped, Cerberus had no intention of expanding any race program.