I'm new to bike repairs but I own a 12 speed 1980 Fuji Sports 12, and I wanted to replace my rear derailleur because the original piece recently got bent out of shape. I'd like to replace the piece but I'm not sure what to buy. I ride mainly for transportation and exercise but I'm not an avid cyclist. I'm on a budget so I don't have too much money on new parts.
Would a shimano 105 fit or is there another piece that would work better?