I recomend that you will get your crankshaft machined for the newer trans. 67-> has the biggger hump on the converter. I have a lock-up trans from 89 behind my 273 and its good.:D
x2.
You have to machine the crank for the 67 up trans. In my 63 Dart I have a 65 273 and a 76 904. The crank is machined to fit the converter. In my garage a B&M shifter waiting to mounted in the 66 up console. The rear end is a 69 8 3/4. And yes, I know it's a crazy mix of parts and model years.