Intake Manifold Recommendation

The 87 has a 207 transfer case. 88 up to ? used the 231. But it is my understanding that the 231 from 88-92 use the mech. speedometer. I want to stay with that if possible.
Basically I think that the nv3500 and 231 transfer will bolt in, in place of my nv2500 and 207 transfer case. Hopefully anyways!!