if swapping my 305 tpi motor for an ls1 , could i use the original 700r4 tranny or wuld i havto swap ?

 

You will have to swap, unless you buy an adapter plate for the tranny to bolt up to the flexplate, and make a provision for the TV cable on the throttlebody as well.

A friend of mine was going to put a Turbo 350 behind a 5.3 liter and after looking at all he was going to have to do, plus $70 bucks for the adapter, he decided to go ahead with the 4L60E