At one time I had a 71 Olds Cutlass with a 350/TH350 combo and an 80 El Camino with a 229 V6. Around the time that I had had enough of the V6 in the Elky, my father-in-law decided to drive the Cutlass into a parked car. Fortunately it was at low speed, it wasn't a direct hit and no one was any worse for wear except for the parked import...and a little fender, headlight and grill damage on the Olds.
Well, I got the Olds back and came about THAT close to dropping its motor and trans into the El Camino. Instead, I came across a Malibu with a 400 smallblock and used that. It's still running fine.
But I wish I would have kept that Olds motor. There's a real good chance it would have ended up in my 63 Nova or 64 C10. I think it would be a great swap and you should love the OD on the TH200-4R. It would also be an unusual swap, yet in the spirit of the "traditional hot rods" that used Olds, Caddy or Buick V8s. Man! It makes me wanna go out and find a Rocket or Nailhead motor.