I've been mounting my bypass filters under the hood. Either near the battery box or on top of the left / drivers inner fender. I made a bracket, so i could pull the whole FS2500 and then change the elementFocus on durability as there is not much in the way of kick-in-the pants gains without sacrificing durability.
Agree with the comment to not use marine injectors. From experience, they gained me nothing other than extra belching at start-up. OE injectors were noticeably more responsive to throttle inputs than the marines. Check with Leroy to see if he has a set of OE's. My vote is sell the marines to somebody whom thinks they are better than they really are.
Toward the parts list, consider a bypass filter. Or better yet a relocation kit with the dual filters.
And consider swapping out the Stanadyne FSD (it is a PMD when mounted to the IP) with a Flight Systems from Leroy. Got another subtle improvement in throttle response when I did this swap too.
When the time comes, a tune will play a huge role in the truck's overall behavior. And, the decision on turbo will make a difference in which tuner to work with.
Oh, and the IP . . . I developed an allergy to reman / rehab'd IP's. New or nothing. I know that some have had good results with reman IP's, but I did not.
If you can find a P-400, it is a tad more quiet than the other variants and supposedly a little more robust. But nothing is really going to make that motor very quiet aside from either going deaf, or a quality stereo system
I install a T in the return line from the engine oil cooler to feed the bypass filter and return to the engine oil fil neck.
I weld a nipple - pointed slightly down - into the fill neck. If you put them in straight or worse yet pointing slightly up, oil will splash out if you remove the fill cap with the engine running