im looking into a new engine unless that i can find some products to boost the horsepower on my 79 six. I am looking for something that while up the horsepower to at least 350 to 375. please help. if at all prices would be good to have along with what website to find these products at. by the way the truck is a 1979 f150 4x2 with the long box

 

350-375 is a pretty lofty goal for a 300 and will cost you some money. You're better off planning to build the engine to make torque, which is what it's designed for. If you build torque the HP will take care of itself. Get a set of headers, Offy intake, port the head and install a decent cam, you will probably be pleasantly surprised.

 

what else could i do to the head to get better improvement

 

If for some reason you want to use the same truck both for towing and for racing, then the 300 is your engine. If you don't ever want to see a similiar engine under an opponent's hood, the 300 is probably your engine. As long as you have some reason for choosing the 300, go for it. Otherwise, the 351 is the way to go.
Just for starters, the 300-6 is heavier than a V8, can not be made to breathe as well, and has a lower RPM potential. There are probably other factors that I'm missing, but Fords aren't really my area of expertise (in fact I'm not an expert on any engine).