I just about to pull my old engine and install a new ZZ4 350/355 hp with 405 lbs torque at 3500 rpms. I spent all my $$$ on the new motor and carb etc and I was thinking I should take my transmition in and get it serviced while it's out. My question is; has anyone ran the 350 Turbo three speed automatic with a ZZ4 hooked up to it? If so will the tranny handle it or should I expect it to fail and force me to buying a Turbo 400?  

It all depends on how sound the trans was/is to start with. Putting double(or more) the torque thru it than original will have some side effects, sooner or later.
It can, however, be built to handle anything you want to throw at it.
If it was working well before, with NO problems, it should be ok...I'd suggest pulling the pan off, and surveying the innerds from there.

Mine worked well but I just changed to  the 700r4 so I'd have the OD and lower first gear....

Thanks for the reply and suggustion.  It was shifting really solid before the old engine decided to give it up.  I only ran the car for 20 miles since I bought it so I don't have any baseline on how well it ran. I guess we will wait and see what the transmisstion shop says upon inspection. If they can build it up would that be better than replacing it with a new 700r4 for the money? 

It would be easier, but better?
Let the debate begin!

I'll be able to tell you if the 700R4 is worth the change in September. My wife picked the car up yesterday and I won't be home until then. Can't wait to drive it.

 Logically though, an overdrive gear that lowers the RPM's SHOULD save fuel.

I'm running the turbo 350 tranny in my car. Like Joel stated it can be built to handle anything. I have 512 lbs of torque at 4200 RPM and after just over 3,000 miles now, it will still snatch a knot in your neck when it changes. (when you can get traction)