Taking a 1965 2bbl 273 to a 4 bbl or commando settings

The difference was a slightly larger mechanical cam, stronger valve springs, pistons, intake manifold, afb carb, straight through 2.25 ID single exhaust, dual point fast curve Prestolite distributor, chrome unsilenced air cleaner, and a high pressure oil pump. I would do all, except the pistons if you are going to use pump gas, mostly on the street. Black wrinkle valve covers, chrome oil breather and chrome PCV housing rounded out the appearance items.