Something like that should be documented in the factory shop manual and parts listing.
I wonder if this was done to broaden the power band and keep it flatter.

Cranking compression might be lower but dynamic ( engine running ) compression could be higher due to better cylinder filling.

There are a lot of sharp engine builders over at speedtalk.com that could help out. ( Mentioning that the car was in Hot Rod would help too. ) Be sure to follow up on this site so the thread does not hang.