Welcome to the forum. Basically, my impression is tin-ware (original tank etc) may not be readily available, but apart from that you can get mostly anything, either new pattern parts, used (ebay), or improved stuff from the likes of SRM. So if it's in decent condition to start with and the price is right, you should have no problems (apart from the wallet getting thinner over time :O)
Post some info\pictures on the actual bike and someone here will surely come up with lots of useful info.