727 question
What is the ratio of the front band apply lever? It's stamped on the side of it. Probably a 2.9 or 3.8 ratio. If it's either of those 2 put 12 springs in the front clutch. If by chance it's a 4.2 or 5.0 lever put 15 springs in it.
I always replace the converter if there's anything at all questionable with it. If the trans. it came out of was toasted it'll have tons of junk in it anyway so the least it would need is flushed.