will a 7.3 work with an b/w tranny?

was gonna buy a 7.3 with a zf 5speed
i currently have a 6.9 with a b/w and a gear vender kit
could i bolt a 7.3 to the b/w rather than use a zf?

Yup!

would this be a good way to fix the dual mass 7.3 flywheel
buy useing one of a 6.9?
and if i ever wanted could i use a zf with a 7.3 with a flywheel off a 6.9?

you need to keep the flywheel, clutch, and tranny together. Meaning, you cannot use the flywheel from a T19 with a ZF5 and vise versa. Flywheel thickness and input shaft length differs and will cause an issue if parts are mixed and matched .
Just remember that the transmission goes with the clutch and flywheel. Everything is the same from the crank mouting flange forward...Even the cranks 6.9/7.3 share the same part #. I first thought you were crazy for not wanting the zf5 but, Noting you already have the GV behind the T19. Just bolt the 6.9 flywheel on the 7.3 and bolt it in. Sell the ZF and associated parts to pay for the new 7.3.

thats easy enof to rember
i didnt buy the motor and tranny yet
i am gonna call and see how much he wants just for the motor