1) Could you tell us more, in detail, about the process of "buying back" a car from the insurance company? How does this work?
2) If i was going to do a swap like this, i would transfer the whole deal to the other vehicle----the complete wiring and ecm(and, if possible, the gauges!). You would have to find new places to mount stuff like the ecm box and wiring, but to me, this would be easier intead of trying to make up my own wiring and then trying to re-program stuff. I mean, you are going to part out the wrecked truck anyways?
So, with this approach, in essence, the 80' will run and drive exactly like the suburban---except it's just in this "new" chassis. And to me, this approach is easier because i consider wiring and re-programing and all that electric stuff to be quite complicated and frustrating. Whereas making up mounts is rather straightfoward. I've done it before; I drew up pictures of what i wanted and brought them to a welder. 45 mins later, i had my mounts which worked great. Simple.
a) I am guessing that you would need new mounts; This should not be a problem if you can weld. Even if you can't, you can always draw up some diagrams and bring it to a local welder. They enjoy building stuff.