x15 emissions/ tuning help

[Loneshaker]

Looking for advice with tuning an x15. I've replaced all kinds of emissions sensors trying to keep it factory and im done with it now. The couple shops that do it locally just say mild to wild and wont shed any light as to what's been best long term.

Motor was over hauled due to number 5 leaking coolant internally about 325k if my memory right. Was done under warranty at a peterbilt shop in WA I think I have the paperwork in truck... anyways. Its a 605 1850. I'm a flatbedder. I debating what tune to run as an isx. I have had hot rod trucks in the past. I just dont know how much these x15's will handle. From my understanding they like their rpm in hard pulls. Im normally about 1550 because of gearing or a little above.

I would like to make this run as well as I can with out having to swap cams or hard parts. Remove all emissions and clean it off the block.

TIA