Getting back to "what they were really like" back in the day, and harkening back to all of the reading I did, IIRC Mopar in the early 60s had the most "race oriented" TOP factory options available. Highest CR, solid lift cams, valve sizes, etc. There was a 2 page chart showing all engine options from Mopar, Chebby, Pontiac, Ford, Olds, etc. and that is where I scrubbed that data and came to that conclusion.
Now mid to late 60s is a different story. Top performance options from Chebby came with aluminum heads, solid lifters, etc. IMO Mopar had great HP/TQ ratings, and the rocker shaft design is so far ahead of the other guys, yet 4 bolt mains were only on the Hemi AFAIK, which is a head scratcher. The BBC head design "seems" pretty conducive to performance and Ford had some pretty big intake valves in a number of their motors. Pontiac intake valves OTOH are generally tiny by comparison, but yet the engines performed well, and is probably my favorite non-Mopar brand of old school muscle cars. The 427 BBC is an amazing piece of work, and riding in a 67 427 6bbl 'Vette is an experience I will never forget. My friend had a 4.11 69 Nova with a 4 speed and a 427, and WOW that is a serious combination of power to weight ratio.
I would counter any of the other manufacturers' offerings with M-Code Hemi powered A-body cars, IMO the all time ULTIMATE engineering design for 1320 performance! IMO the Hemi is the last word on the best engineered production motor of ALL time, as evidenced by the design still being used in Top Fuel/Funny Car although none of those parts are Mopar, they are a copy of the design concept.
Yes, lots of amazing engines and cars from back in the day. I would be negligent not to mention the 413 and 426 Max Wedges. Incredible intake and exhaust designs-dual quads on 3 foot long intake runners, cast iron long tube headers w/dumps stock from the factory, those giant intake ports...
I am very happy with my 440 6bbl. It too is one of the very top performers from the era and a pure joy to put my foot into. I know that in my 70 Roadrunner with the Dana 60 I have a great platform for traction and 1320 performance for the 440+6 to shine. IMO B-bodies "naturally" perform better than other body styles when dealing with STOCK setups. I believe that it has the widest tire capacity without modding/tubbing and great weight transfer. If it was lighter that would help, but the Roadrunner is lighter than other B-bodies unmodified. I would like to have a 426 Hemi in another car, but my V-Code Roadrunner is more than I thought I would ever have, and is so great I don't "pine" for anything else.