3 to 4speed swapability?

I don't know what "shop balanced" is but if the bellhousing has both bolt patterns, it would be one item to grab along with the dust covers. I would get the clutch fork, clutch assy, and flywheel too even if you have to have it rebalanced for an internal 340. If your car is an A-body, not much else will do you any good. If yours is another B-body that year, I'd get the pedal assy, clutch linkage, steering column, and floor hump.