I would advise against using a stock used 200R4. They are usually junk. They were junk when new. Not going to hold up with any hard use at all. These trannies need to be beefed up to handle a strong V-8.
On the other hand, since I believe you have an OHC6 this would be acceptable. These transmissions were used behind V8 Olds and Turbo Buicks. It should hold up fine in this case.
They didn't hold up with the V-8 Olds or even the wimpy deisels. I've swapped countless 200R4's for people. I believe the Buick Grand Nat's had the beefed up version. I had a 78 Turbo Buick and the trans puked on that too and it was just a 6 cylinder.
