I may have to order some parts for my son's PT1911 if he comes down for Christmas. That would be a cool father/son project. It looks like a hammer, trigger, and sights would be a good start, any suggestions?
Hard to go wrong with parts from makers like Ed Brown, Cylinder & Slide, EGW etc. I would advise to go with forged parts and if you get a hammer, then pop for a kit with all the group parts, i.e. hammer, sear, disconnector. When using a "drop-in" kit from reputable manufacturers, very little final fitting (if any) is needed.
Both Brownells and Midway USA carry a fine selection of 1911 parts and most makers sell then directly. Both have great technical pages and you can also call them with questions and they can help you with selection ideas.