I run the 75cc ones, purchased many years ago, maybe within a year of them coming out but just started running them about a year ago, swapping out the 84cc regular Edelbrock heads in order to get compression up. To further increase compression I'm using them with mr gasket steel shim gaskets that came with a paint/coating on them, and so far they've been fine for about a year, driving the car every few weekends. I didn't do any real inspection/teardown of them as you might hear recommended. Same with the regular 84cc Edelbrock heads, just bolted them on too, no problems.
I am running them with Comp cams version of the purple shaft 292 .509 cam, on what had been a very low compression 440 in a '67 Dart. Now it's just low compression, I think a little over 9 at this point. Never ran it at a track but it feels good and fast.