I have also owned more muscle cars than I can count (had twelve licensed and insured at one time), but they were all Camaro's or Nova's with the occasional Corvair or two in my fleet at all times because I liked how they drove. I have never owned a Chevelle however, and I can not think as to why I never even thought of them as being too portly, but considering I jumped into Impalas after I owned my last Nova race car it is hard to understand.
I still have one '77 Nova project car that is complete and ready to drive. I acquired it from my from my Dad when they offered him only $150 in trade in value. He bought it new back in 1977 and put 3000,000 miles on it. I also own four third gen Camaros that I bought for $150 each just to keep them from going to the crusher (the IROC Z/28 has rear disc brakes that may find there way onto the Nova at some point). I figure if I wait thirty or forty years I might get my money back. Add to that a 1973 Mercedes Benz 350SL convertible and two four wheel drive three quarter ton HD Suburbans and my barn is starting to get crowded.
My brother currently owns a 1969 two door sport coupe with a Merlin 509 built by Bill Mitchel that he bought from a restoration house in Clearwater FL as an all original 1969 SS 454 car.
It is a very nice car, but not exactly an all original SS as claimed by the used car salesman he bought it from. It was pieced together and given a pretty paint job from a Malibu body, and sold with a computer generated window sticker properly torn and dirtied up and made yellow by soaking it in tea inside a page protector to list all of the options including the 454 engine that has Merlin III cast over the timing cover. But then a fool and his money ... My brother has lots of money, but no sense. Caveat Emptor