ok i just read your build thread.i don't want to offend you but it's a truck i would have passed on for the foundation.as someone else there stated,there are no shortage of these trucks out there.with all that said,it looks like your doing a super job and having fun! i say keep at it now.it's going to be a nice truck when done and it'll make ya proud.
i see some key things there that scream hell no,this truck isn't worth a 4k reman n/a idi engine plus the turbo and intercooler costs on top of that.those two vital things are; the ownership duration plans are too short.your building up a truck you won't be keeping long and getting into a crew cab eventually.true you could swap it,but plans and years change things.by the time your ready for that,you could very well be ready to move away from the old idi by then too.(i know,i know fans.it's hard to believe this thing happens lol.)
plus you mention the trucks just going to be driven but a few thousands mile per year.
with the condition of the truck,the age,the plans,the most obvious,clear logical choice that i personally would do,without a second thought,would be to grab one of your already good running engines,install the cam from Russ,and search for a used turbo.put her together and i think the odds are the engine outlasts what you have planned for the truck and then move on to a newer truck.
in the end,it's on you,but i suggest you don't spend the 6-8 grand into an idi and just have a couple hundred hp engine,that would likely last you as long as a used engine would for your couple thousand miles per year.
there are members here who purely run used engines for business and get super high multi thousands miles out of these things.it's your coin.good luck either way.