i would say take the plate out, do the Mack rack plug, tune your afc, 4kgov. spring, do a 4 or 5inch exhaust. as for the clutch if you want to say under $1000 for a clutch you will have to do a single disc. i would do the valair k/c 13'' flywheel that will hold 500hp. set your pump timing to 16-17 degrees. the stock hx35 will get you to 400hp but you will have to push it hard. i would look at and 60/60/16 which is and hx40 or a 3rd gen turbo from and 04.5-07 cummins. injectors i would go with a set of 215 out of a 96-98 12v 5speed or if you have the money do 90hp injector.
this is how you tune your afc