Complex: you could be right. I've never compared them side-by side. I've always given 305s away. But according to numberous Monte Carlos SS boards and sites, the heads were different on the SS.
I still have an 85 Monte SS, but the 305 and heads are long gone, otherwise I'd check. Here's one page written by a guy I've known for years and trust ( Paul Carreiro):
http://www.montecarloss.com/SS_FAQ_1.html#2 It includes the "Cross Fire Heads" info.
Again, If I could compare them side by side, I'd do it...but right now my Monte Carlo has a roller-cam AFR head 406 in it and is being prepared to run on the Salt Flats.
