The best thing to do is go for the header. And, since you have a 1-Bbl set-up, you should also switch over to a 4-bbl intake and carb to go with it. With that, a bigger cam would certainly help. Then you should think about slightly higher compression by switching to either a 230 1-Bbl head or the 250 4-Bbl head. Some mild porting and a set of better valves and springs, and you'll be all set!
To remove the flapper you will have to grind away two hot rivets, then cut the sahft adn plug the two holes in the exhaust manifold.
