That is indeed a replacement fork, and the rusted area (caused by blistered paint) at and behind the top tube lug tells me the bike was in a head on collision. I was going to say the frame was not much affected, but I decided to check. The pic below has a black line next to the head tube that is parallel to the seat tube.

These bikes were generally built with parallel tubes or close to it, so you can see that the head tube is canted more vertical than it probably was originally. That will change the handling somewhat and also reduce the clearance between your toes and the front wheel. I would say you need to ride it and see if it pulls to one side and if the handling and toe clearance is acceptable. Otherwise it's a decent bike, but one other thing can up the cost quickly, and that is the chain. You need to take a ruler and check for wear, then factor in the cost of a chain and freewheel if too worn. Measuring Chain Wear

The Bridgestone is overpriced, as I think that is their low end model. Unfortunately it's getting to be the wrong time of year, but garage sales usually yield better deals than CL.