Is my engine performing as it should??

You have heavy valve springs, ported heads, and a stock cam. I'm impressed it revs to 5500. I think you may want to try shifting at 4500 and see what it does. The heads hurt 60', as does the stock convertor and gearing. I would replace the springs with a set of Comp 901s (single with dampner) or remove the inner spring from the heads, install an XE268H and try again. It's making decent power for the cam. But you put in a stock cam. Now it's wasting power opening against the big springs and the ports are not moving air well at low rpms. Typically porting sacrifices low lift flow for mid and high lift. Good portting minimizes that effect. Average or poor porting exagerates the effect. Minor mismatch... address those two and see what it does...