As you have discovered, there was a lot of evolution down through the years, and many newer starters will fit older motors. So, we don’t even know if your starter is original to the motor. 1957 was the first year for 12V starters, and the truth is they weren’t all that great. They were just adequate, and were easily damaged by stalling them or cranking for extended time.
I am presuming you may have the MDO which is where I got the 170 figure. But look at the difference between MCO and MDW specs. The MDW draws fewer amps but has considerably more ft/lbs of torque. Sorry, I don’t have a chart for newer models.
