Believe it or not....many engine and related parts will be available right at your local parts suppliers. AutoZone and Advanced and if they don't have it try NAPA. It doesn't cost anything to give them a call, but better yet, go to the store, find the oldest guy, preferably with a gray beard and thin hair and he'll walk through the books and fulfill your needs. I found that they had starters, generators, water pumps, ignition parts and could get engine rebuild parts at as good prices as the mail order folks without the shipping and waiting for the UPS truck.
I've used all the normal mail order houses for body and specialty parts...they are all dealing with the same suppliers and their prices are fairly competative. Sometimes the solution to your parts needs are right under your nose!!
Dave