One of the great things about owning a C3 corvette is that you could probably completely build one from parts from any of a wide range of parts suppliers, including GM (your local chevy dealer). If you're looking specifically for performance parts, your best bet, though, isn't necessarily to look around 'corvette' parts suppliers -- like another CAC member pointed out to me, the Eckler's, etc, of the world will sell you performance engine parts (cams, heads, etc), but you can get them cheaper direct from the manufacturers. To answer your question: I agree with 71Shark, the Portal is a great first start, I'd make sure to check Jegs.com, and depending on what you're looking for, Compcams, Crane cams, Edelbrock, etc. For restoration parts, etc, make sure to check Eckler's, Mid America, Paragon, and Corvette Central.