industrial slant question or two

Measure that crank counterbore more carefully. '67-down is 1-1/4", and '68-up is 1-1/2". You can use a 1-1/2" (later) crank in front of a '67-down torque converter by dint of an adaptor ring that's not hard or expensive to get. You cannot use a 1-1/4" (earlier) crank in front of a 1-1/2" (later) torque converter, and you cannot swap in the earlier torque converter without also changing other transmission hard parts.

Other than that: Yep, everything's the same. Swap on your car-type bolt-ons (oil pan and pickup, dipstick and tube, etc) and off you go.