Are you talking 360/340 Mopar? Completely different crank.
If you find a reconditioned AMC 360 crank and you're using stock pistons and rods, then it's probably close enough for a daily driver rebuild. I doubt you'll find a new AMC 360 crank without spending lots of $$$$. The AMC 343 has a shorter stroke. Some rebuilders sell them already turned with correct bearing sets. If you're doing a bore and adding aftermarket pistons, then I recommend a balance, as aftermarket pistons are usually quite a bit different in weight from a OEM factory piston. This is the same reason I would have it balanced if using a 304 crank in a 360. The difference in a 3.75" vs 4.08" bore makes the 360 pistons heavier.
My machinist balances the rotating assembly down to 1/2 gram. There are 31.1 grams in an ounce. My machinist charges $150-200 to balance. I believe it's worth it just because it runs smoother and will last longer.
Bob
tufcj