I have a novel idea - Ebay Motors has a lot of these engines for sale and quite a few pics. See if you can decipher or get the Chevy symbols from them. Is a little painstaking, but you may actually enjoy doing this!
I've seen a symbol with a triangle on top of a rectangle on the head - it was a 1962 327ci engine I think. Looks pretty plain but I guess an auto enthusiast will love it.