I am here also and have owned a couple of chevelles but not the expert..
.. grew up in tucson, there used to be some really fast cars down there.. a nickey and some copos at the local speed shops and one of the mechanics the family knew had a gold copo that really rocked. too much horsepower for our chasis dyno back then.. I don't remember details except they couldn't keep traction on the drums with the cheater slicks on it but remember all the mechanics talking about it when I was a kid.