There are different ways to solve the wiring issues. One is to just swap it all out, and some dashes will adapt readily into the Kickers. While that is a lot of work, it should resolve most issues with where to get power and where to send signals.
Another way is to integrate new and old systems. While it seems that it would be much easier than unwiring and rewiring the whole vehicle, it is more complex as you need to find where signals come and go in both systems and splice them in. This means going through both wiring systems and finding where they best mix. And getting one wire wrong can fry the whole system, or not and just leave you with a problem to solve. And trying to do it neatly is a tremendous undertaking.
Or you can install new system as a stand alone installation where it runs independently. But, it won't be long (probably before it is running) before integration begins because you want information on your dash.
Wiring is the most time consuming element of the swap.
Installing the 2.7/2.5 motors in the pre 99 kickers is a tight squeeze if you want to keep IFS. It can be done, and is much easier with a diff drop and probably even easier with a body lift. Installing a hydraulic clutch will take some consideration on master cylinder placement. I ran on a copper tracker radiator for a couple years, before going to a bigger radiator. I had to use a pusher electric fan, as there is not enough space for a fan between radiator and motor. Get a good fan and it will cure a lot of overheating issues.
Getting together with beagle would be good for both of you. When I was doing my sway Muskegtracker was also doing one, and knowing that someone else was solving the same issues gave us some answers or alternatives to problems.