Teflon sealing rings for input shaft.

Is it worth it? or should i just install the steel rings in the kit? In the process of assembling this transmission

Bone stock. Metal rings are okay, if that's all you have. Anything else, teflon.

The teflon rings expand to fill the groove and do not wear the stator support like the steel rings will. But, the steel rings work fine if the groove in the shaft is not damaged. Check side clearance with a feeler gauge the same way you would piston ring side clearance.

I only use steel now, as in the past I have melted Teflon rings being on trans brake at 5500 rpm with pro tree

Teflon are a no no with aluminum drums. The steel will work very well if you lap the grooves in the stator support. If the grooves are tapered the rings will wear on the side. Never had any issue with either style on the input shaft.
Doug

Guess i should have mention this is a transbreake race transmission, with aftermarket drum, if that even matters, I'm getting ready to pull the trigger on some parts from john cope transmission.

Thanks For that advice Doug.