are any 340 and 360 parts interchangable?

The only parts that don't interchange between 340 and 360 are: oil pan, block, crank, main bearings, rear main seal, oil pan gasket, pistons, rings, harmonic dampener, torque convertor. The rods are not the same (340s are a little heavier and have the pin bushing IIRC) but will work if you are having them re-done and the assembly balanced.
The balancers for 360s, and cast crank 340s carry the words "Use with cast crank 340 only" or the same but "360 only". The forged crank 340s and all 318s use the same balancer.