transmission swap

I have a true 1970 El Camino SS the factory engine and transmission is a 454 with a turbo 400 auto. The old engine is old, I replaced it with a nice 383 stroker for the timebeing. The turbo 400 is plenty strong but it takes too much away from the high revving stroker. My question is would a turbo 350 fit in the elky where a turbo 400 once was, and would i have any driveshaft length issues. Dont worry i will rebuild the factory 454, I pulled it before i cratered it. And yes I do drive the car.

Both transmissions should be the same length, somewhere around 29.5" long. There were longer automatics, I know the TH400 came in a longer length for the station wagon towing package. If the lengths are the same, you should be good to go. If you have a spare TH400 driveshaft yoke, or the one out of the car, take it with you when you check out TH350s.

Bob