I tore down the top half of a 460 out of 1995 F-350 so I could have the machine shop extract the broken exhaust manifold bolts. After putting it back together (to include a Banks Exhaust system), it fired fight up but seems to lack power and is back firing (more like a loud pop) inside the cat. Other than setting the timing and making sure I had the firing order right, I ran out of day light to check anything else.

Where do you think I should start looking? Thanks for your help.

 

I would look for a vacuum leak. Take a can of carb cleaner and chase your intake gasket area. It'll sound different if you find leak.