I wouldnt be so pessimistic - I've seen motors smoke with low/broken/worn brushes before. Usually you'll see that the commutator/slip ring gets burn marks (if thats where the sparks/smoke were from)
use "crocus cloth" (or >800 grit sandpaper) to polish those surfaces back to a very smooth, bronze finish
Normal solder (eutectic or 60/40 should melt at 360-something degrees
Solder - Wikipedia, the free encyclopedia
Most industrial motors (single speed, 3600 or 1800rpm, any voltage from 480v to 13,000v) have high temperature alarms in the 170F-270F range - above that you are hot enough to deform the windings. I have no idea how much your 120v motor is like this (what kind of glaze/insulation, winding thickness and alloy etc.)
I'm afraid this isnt helping you much - 270F and 360F are kinda close. remember that at 212F water will boil off if you hit the motor with a drop (obviously not a stream of water). IIRC you can hold something at up to 130F or 140F depending on how baller you are
That being said - I'd solder it and make it run. YOLO
-John