"Power Mods for MOPAR's 273 {February 1966 Hot Rod Magazine}
Herb,
Great Stuff.
Back in the Day, the weak link for the 273 was the Clutch Set-Up.
The Auburn Pressure-Plate {9.50"} was a poor unit, and was only rated at #1650 lbs.
of Coil Pressure.
And the Clutch-Disc {9.50"} only had 75.8" of surface diameter, with .114" of thickness.
At the time, only Weber Speed Equipment {Santa Ana, California} had Clutch Packages readily available.