Hi Joe,
I'm no Ferrari expert, but I don't think there were any factory 250 GTO Spyders, just some conversions of other Ferraris re-bodied. For my car, I found out details from some of the Ferrari forums around. There are some pictures of one of the Spyder replicas at Ferrarichat that you can see here (you have to register for the forum to see the pictures, but I found it worth it):
250 GTE/GTO
Most of the Ferrari boards don't have a high opinion of replicas, but there are photos and information to be found. I've gotten Ferrari parts and replica parts from Ebay from time to time and reading through this thread on 250 GTOs right here is a gold mine of information.