Flexplate orientation/Transmission to engine mounting?

cosgig said
That is only a problem on the 273 engines. The register is smaller on the 273 crank, and the corresponding torque converter about is smaller. And the trans for the 273 has a different spline count on the input shaft than the later 318/340/360

The year was 1967. 1968 was the change over. Like always at this point in time, measure both.