I have a 66 C4 auto and a 200 I6. I am no expert on transmissions.
I'm having trouble shifting after a rebuild.

I'm looking at getting a C4 from a 68 and a 302. Can I swap out the bell housing and use the 68 C4 on my 200 I6 ?

Also would it be possible to swap out the valve body. Which could help me get away from the green dot 66?