Wow, I got lost in that.

360s had quite a bit of factory imbalance and used a neutral balanced flexplate with an imbalanced torque converter. So the torque converter needs to spin with the crank. This isn't too attractive to someone who isn't used to it, and I wonder if it's safe at all. Maybe someone else will tell us it's done every day.

There are flexplates with the factory imbalance built in. Then you can use any neutral balanced converter. I think doing this would make most sense because the crank would be balanced to factory spec. Torque converter selection becomes so much easier.

Another approach would be to use an LA360 flywheel for balancing.

Blazin' Bob always suggests neutral balancing the 360 but that will involve using Mallory Metal (tungsten) to achieve neutral balance with stock bobweight. I think you're looking at close to $300 extra to neutral balance the 360 crank with a stock bobweight.

Something else for those who haven't already bought pistons, is to use aftermarket rods and pistons which can save 200grams per cylinder, and then I wouldn't be surprised if that 360 crank would neutral balance without costly Mallory.

One more thing: There are at least four different amounts of factory imbalance and they are not the same at all.
Cast Crank 400/440
Cast Crank 340
LA360 (all had cast cranks)
5.9 Magnum (all had cast cranks)

I hope you find your way through this mess.

R.