Compression

rumblefish360 said

That’s a great demonstration of how weight affects the engine and how, as you said, timing is critical. I see a 1/2 point lower compression 10* in cam duration @.050 and an added 1,000lbs. is where the boarder line is approached in this particular case.

A case can be also made on the cylinder head chamber shape/design & quench.

Click to expand...

You zeroed in on a big part of the difference in the two combos too. Aluminum heads with a (sort-of) modern chamber, and quench.
The 440 has a 70 year old chamber, piston down the hole a bit, NO quench, and a small dome. It SHOULDNT work on pump gas. Big gear (has had 4.56, 4.11, and 3.91) and a 4500 converter helps.
A typical 225 at .050, 3800 lb 3,23 street combo, would be a disaster at 10.5.