727 No forward or reverse

Plate clearance, I have always targeted a minimum of .010 per friction.The FSM lists the clearances as all over the place from ridiculously tight to ridiculously loose.
For the front clutch; 3discs are .036 to .086, 4 discs are .024 to .125 depending on application. See what I mean
For the rear clutch, the spec is .032 to .055 for 3 or 4 frictions.

I wouldn't be in a hurry to condemn the lip seals, as I have seen the same thing in perfectly functioning trannys.There are at least two different styles of lipseals for those and one of them in particular fits fairly loosely.
Cast rings however need to have plenty of room between the hooks, before you install them.I always prefit them.
I wouldn't reinstall the tranny until I knew why the front clutch burned up.
And you still need to figure out why no forward gears. Since the rear clutch is engaged in all forward gears, that would normally be the go-to. But since you say yours is fine; that points back to the L/R band.And since the L/R band is used for both Low and Reverse, it now becomes the Go-to item. So you will have to pay particular attention to the hydraulic circuit. Or perhaps the servo was all out of travel, due to a waaaaay out of adjustment L/R band