I have a 72 olds 442 the engine is 455 with a F block and G heads the carb is an edelbrock # ending with 251 I want to leave the stock look but give it more horse power and have a set of flow masters and a 323 posi rear with a th400 tranny with a slap shifter any input would be help full

 

You can put an aftermarket cam in it. You could also put higher compression pistons in it. If you don't want to do mechanical engine work then you could always add W/Z manifolds on it (or a set of headers if you don't mind going non original). Don't forget you can also add an aftermarket intake manifold and paint it to match the engine color.

 

Its all about the money when you seek more HP. As said above hotter cam, rework the heads with bigger valves, higher compression pistons, adjustable valve train, intake manifolds, etc. There are a number of build threads in the big block forum with great detail. Take a look there then narrow you questions down and think about how much money you are willing to spend. We can go from there