There's general expectations, but ultimately, the only way to know is to try. Good to have an assortment of spare parts to test them out for best possible fit. The parts that always seem the hardest to come by are the caps, in my experience. You might find 20 barrels for every crack-free cap.
Sometimes pens with the same model number could be made decades apart, in different countries, with different machines. They might be very close, but close doesn't quite cut it when you need an airtight seal to keep a pen from developing leaks. There is a lot of variation in the feeds over the years, in particular.