I am asking for my brother-in-law who has a '81 cj with a t-176 that has gernaded. What would be his simpliest options for replacining this tranny?

He has a H/P motor and a dana 300. He would like to keep the same bell housing and drop out the t-176, do a direct swap to something like a t-98,t-18,sm420, or sm465. Would any of these direct bolt?

Without getting to involved, I will say that the motor is a chev-350 (with an adapter plate).Would the sm420/sm465 be simplier as it would bolt directly to the motor? Will these trannies bolt directly to the d300?