Is there anything to rebuild/tighten in that fitting that comes directly out of the EVO???
That two-part assembly where the barrel spins on the (relief valve) stub that goes into the port on the pump relies primarily on the internal o-rings to seal, not compression against the pump (or each other) when assembled. It only spins to allow for assembly and perhaps as an additional strain relief during engine movement. A 'rebuild' amounts to inspection, cleaning as required and o-ring replacements, I think.
If there were actionable metal wear, I'd assume it would be where the o-rings fit, but I can't imagine it getting to that point....the o-rings are the wear parts and fresh ones will tighten things up a bit. I'd want to know that the o-rings are fresh and of the correct size, etc. Speak up if you haven't found the part #s, etc.
Of course there could be examples where the two parts have been damaged separate from in-car service that might contribute to a chronic leak, in which case close examination and/or an outright swap to another assembled fitting might be in order.
I installed a fresh pump and o-ringed my EVO last year since I was in that far and I have some spares, being forced to buy a package w/minimum quantity. I was rewarded for my good effort by a leak at the housing, tho, so I need to go back in and have that pump warranty-exchanged, so those spares will come in handy now.