273 manifolds

I've been running the stock 273 exhaust mainfolds on my warmed over 360 for about 15 years now, and although they're obviously not the best flowing system around, they should be just fine on a stock 360. Mine is a 66 Valiant so, same weight etc, as yours, and I've blown away many an unsuspecting off-brand street hero with just my old 273 manifolds and a 2 1/4" dual exhaust system. :) Sure beats cutting up my inner fenders.