Help!

The pilot on the early 904 converter (1960-1967) measures 1.550" and all later converters had a 1.810" pilot.
In case you're wondering, NO, YOU CANNOT MACHINE THE PILOT DOWN", because it isn't thick enough to take any machining.
Your choice is A: get a custom converter made, a later one to fit the transmission, but with the mounting cover with the smaller pilot.
B: Use an early transmission.