IMO....this 1975 race car represents what "Pro Stock" should have been left as in 1973 and still be....a "professional" version of (sportsman) Modified Production". Factory unaltered sheet metal (except expanded wheel / tire openings) with strict limits on needed modifications to install the race cars manufacturer naturally aspirated motors and manual transmission (no Lencos). Lbs per cubic inch...all the same.
JMHO....yours may very.