The Offenhauser adapter from Ford block to Chev transmission shown above is still available, at least at
http://www.summitracing.com/parts/ofy-5272 and likely other sources. They seem to be aiming at people who own an early Ford and want to put a more modern Chev bolt pattern transmission behind the flathead. There is also a 5174 part # as well as the 5272, I have no idea which (if any) better fits the Chev transmission in the CMPs.
Has anyone seen a modern source for the front mount plate shown? I'm not in a rush to do it, just curious if the parts are still "off-the-shelf". The next obvious question would be radiator and mountings, then how it would fit in the CMP cab since the Chev doghouse/engine cover was narrower than the Ford when I last measured.