I have a 70 Challenger that I am modifying instead of restoring to 100% original. I have a complete sunroof from a 73 Challenger that I was planning to install in the car. Here is where I have questions. Since the car is not going to be original, should I use the factory sunroof or one from BMW, Volvo, newer Charger etc? Are the original Challenger sunroofs hard to get parts for? Are they hard to keep working, etc? Thanks,Tod