340 to 360 Harmonic Balancer Swap?

OK Got it all figured out. Here's where i got confused. The 340 with cast crank is EXTERNALLY balanced. From the factory that would mean the harmonic balancer was the special "use for 340 cast crank only" and a balanced torque converter.

However, the 340 I pulled had an aftermarket balanced flex plate on it. Meaning the torque converter had been replaced w a neutral one.

Thats good news for the 360 Im putting in. I kept the neutral torque converter in and used the stock 360 harmonic balancer and bought a 360 balanced flexplate from B&M that would bolt to the 904

So, thanks for all the help. I got it together. will give you pics soon.

God bless
keni