Shorties aren't a bad idea. Long tubes would be better, but, more expensive to get the exhaust complete. Going with shorties, and a stock y-pipe, which *should* include the cat, pretty sure it has a 3 inch outlet... just run a single three inch pipe to your muffler, (however loud you want....) and then you can do dual outlets, or a single, whatever trips your trigger. The single 3" will flow better than 2" duals, and be cheaper. 2.5 inch duals would be nice, just depends on how much ya wanna spend. Larger diameter pipe also gives a deeper tone.

As for the cam, gotta decide which intake ya wanna go with. Getting something that will rev to 6K RPM and using the kegger intake would be a serious waste.

 

Lots of folks use the 5.9 magnum engine (since it has a hydraulic roller cam stock) in vintage cars and go with a new intake & carb instead of fuel injection.

As for camshaft selection, it really comes down to what you truly want performance-wise out of your motor and how much money you want to spend.

 

I run JBA ceramic coated shorty headers that I found used on Craigslist some time ago. I use copper header gaskets (https://www.jegs.com/i/JEGS+Performa...10456/10002/-1). The headers bolt right into the stock Y-pipe and fit like a glove. From there, I installed a Magnaflow Converter - 99047HM (dual 2" inlets, 3" outlet, front O2 sensor port). A length of straight 3" pipe comes off the back of the catalytic converter and into a Dynomax UltraFlo Welded 3" Muffler - 17233. An O2 sensor bung was also welded into the pipe between the cat and muffler for the rear O2 sensor. A 3" tailpipe was fabricated to come off the back of the 3" muffler. I'm very happy with the 3" cat back system and it isn't too loud for my tastes.