Mating a 4 speed to a slant, question on years

This is kind of an A body question...

I have a '50 Fargo pickup, I'm in the process of installing a great running slant 6 I have into it.

My plan is to use the slant, along with a New Process 4 speed and bell/clutch/flywheel I've got.

The slant came out of a friend's '74 Dart, and the bell/flywheel/clutch parts are in a '66 W200. Am I running into balancer issues with the flywheel? Does that year slant use a cast crank, and say the flywheel may be a neutral balance?

Thanks