Well, I don't know if I'd go that far. That front bearing retain diameter changed over the years and it needs to match the bellhousing. Also, the output went from a ball and trunnion U-joint in the '64-5 models, to the 25 spline slip yoke type in '66-7, to the 29 spline one from '67 big blocks and later. Nothing that can't be overcome, but, it's just more hassle and money if you pick the wrong combo. If the OP is just going to use the car on the street, building a stronger small clutch is also an option. The '70's B-van slant 6 clutch fits the early flywheel, and therefor can use the stock '64-6 cast iron bellhousing and clutch linkage. Another thing you might want to verify is that the crank has been finish machined for a pilot bushing. Otherwise, get the later Magnum bearing instead.