Mike,
In 1965 thru 1967, Mopar should have offered the 273 in both a 210 HP and 235 HP version.
The original 235 HP 'High Performance' was overated by 25 HP.
Yes 10.5-1 Compression ratio pistons, but the solid lifter camshaft and small
carburetor limited it's performance.
The Carter AFB (500 CFM) and low-plane 'X-design' cast iron intake worked
well in the low and mid-range levels, but not on top-end.