'91 GMC 'burb 4x4, need help planning project

[a58chevy]

I have a '91 GMC Suburban 4x4 that I bought to haul band gear with for $1500. Body is in great shape but this weekend I think the timing chain jumped and I think I bent a valve on the freeway. The trans also was leaking pretty bad.

It currently has a tbi 5.7 with 700r4. I want to go 5.3 or 6.0 depending on cost and availability.
So I've never owned a 4x4 (don't plan on doing alot of off roading, mostly for snow driving ability) so I want to know what exactly I need transmission wise. If I buy a built 700r4 are there any specific needs for 4x4?

This will be a carbed swap. I have the carb aspect figured out but I have some more questions.
1. header suggestions?
2. what motor mount adapter do you guys prefer?
3. how do i run a belt with ac delete?
4. do you guys run the new style alt and ps pump or use vehicle stock?

any other tips you guys have will be greatly appreciated.