I have never been a real NASCAR fan but did keep up a little during the 60s. I remember Fred Lorenzen and Fireball Roberts driving Fords.
I also remember was it 64 or 65 when Chrysler let loose the King Kong engine. I never really understood why the Hemi outperformed the Fords but it did.
One of my best friends had an old Chrysler with a 413 and two four barrels. I think it was actually a hemi too.
The 413 is a wedge engine, known because the combustion chamber shape. Hemis breath better than wedge engines usually.
The original “Hemi” was named for the hemispherical combustion chamber. This resulted in the use of large valves that sis not suffer the normal shrouding issues of a standard wedge arrangement. The valves were aligned in opposition rather than side by side.
Together with the centrally located spark plug, the arrangement resulted in the use of higher compression, better flame front travel and better intake/exhaust flow (breathing) because of reduced angularity of the ports.
In simple terms, air/fuel entered and exited much easier and made more efficient use of every power stroke.
The problem with the design is that it takes more hardware and is physically larger (note the width of a valve cover on a hemi vs a 413/wedge design. But in the overall, a hemi will make more power and ‘enough more’ to overcome the size/weight issues.
Probably a Max Wedge or "semi hemi"