Actually, the USAir 737s were originally supposed to be delivered to Canjet, but Canjet folded and was also unable to reach a leasing agreement with US Airways.
I doubt that they'll go to WestJet apparently because I've heard that these USAir 737s have different engines from the ones in WJ's fleet, so WJ doesn't want them. At least that's what I heard, so don't take my word for it.
Yes, Spar Aviation is doing the overhauling now with these 732s. Spar specializes in servicing older aircraft, so you may actually see the occasional 737 or 727 at YXD. What strikes me as a bit odd is that these 737s have been sitting by the hangars for months now.