had a better look under the swift today, and repairing it may not be out of the question. it's not as bad as i thought.
did an eyeball wheel alignment in the driveway and now the car drives pretty much normally: tracks pretty straight, no tire squealing. the reason it was so far off before is because whoever did the control arm mount repair didn't line it up properly before welding the patch in place.
everything in the car works. there's a bit of a gas smell around the tank area, and a leak in the exhaust. and the front tires are shot, of course.
i'll have to get my mechanic's opinion on whether it would pass safety with the floor/suspension mount area properly aligned, welded & reinforced. i've always wanted to try welding...