First off, why would you get rid of the O2 sensors? You do know that removing those will kill your already poor gas mileage. Any tuner will tell you to put those right back in, or put a/f sensors in there.
No need to go to a dyno, everything you've done is bolt on, its still basically stock. There are two major people who tune these trucks. HemiFever, and Flyin Ryan. Hemifever has ok tunes, but they are lacking in some areas. Flyin Ryan is basically a professional tuner, I doubt anyone knows how to better tune a Magnum engine than him.
Things to consider if you want more power. Get rid of that crappy kegger intake, the thing is crappy flow wise. There are a couple intakes that will make some nice improvements and really make a tune sing, you just gotta dig around for them. The M1 is generally the favorite around here, but finding them is impossible, and expensive. edelbrock air gap is the next one i'd go with, Hughes engine parts are crap, except the plenum repair kit (you have done that right?) but a felpro gasket and new plenum bolts fix the problem for a lot less money. The stock heads are also kind of crappy, they crack between valves, thats a guarantee, if you have low compression, thats likely the reason, and they don't flow well. Decent headers and intake can help, but the best racing headers and intakes in the world wont make much power on these heads.
Those are things to consider as you go forward. I mentioned it earlier, if you haven't done the plenum fix, do it now. Ryan basically won't talk to you if you havent fixed the plenum.