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!...