Stock magnum bottom end with tricj flow heads what cam?

First off........what do you mean by hold it's own? Against what?

Budget to me means you don't spend a dime you don't have to and you adhere to the principles of KISS............

84k miles on a magnum is peanuts; can you/ did you do a compression/leak down test, if it passes that, I'd have the cam that is in it reground ( as a Magnum I'm guessing it's a roller hydraulic) to a sportier profile, OR up grade to what was put in the 360 hp crate engine.....go have fun