I've heard it suggested many times that Bock was considered for the title. I am skeptical that he was ever outright offered it and turned it down. It's more likely that a promoter of note/player in the NWA mentioned to him that he might be someone of interest and he let them know the feeling wasn't mutual. AWA money was good and travel was lighter. Plus Bock was able to book himself out to other offices (Calgary, Memphis, Houston, et.) whereas in the NWA he would have been at the whim of the NWA promoters, with the NWA president taking a percentage of the cut as his pimp.
Bock has said in shoots and interviews that it was suggested to him that he could have been in the running to get the title, but I always got the impression that it was more of a late 70's thing, as opposed to 1982. Bock thought about it and was interested in the idea but, as you noted, he figured out how much the NWA Champ made and how much he worked, and compared it to how much he was getting from Gagne and how much he had to work in the AWA, and quickly decided that it was not worth it from a financial standpoint, or a quality of life standpoint. Plus, as also noted above, he could fill holes with individual shots in other areas when he wanted to do so, on his own schedule.
I've always heard that it would have happened before 1982, though.