Hi "Fourdy", the compressed thickness on the Fel-Pro's specifically, numbers 1055/1056 (copper, photo below) is .058". This is a "nominal" number, could vary a "thou" or so!
The "relaxed" thickness is .062". I would assume any "composite" gasket would also be in this area? Generally speaking you will lose about .004" when torqued-up!
Thanks, Gary in N.Y.
P.S. Can't help on any Edelbrock gasket dimensions, we don't use that brand here at all.
I checked some Fel-Pro composite gaskets when I was fitting my Edmunds heads and they were also .058 compressed. When you think about it, they should all be designed to end up with the same compressed thickness.