v-6 in early A-body
It didn't start anything...
Grissom is apparently offended (or at least put off) by "foul" words, and Magnum is easily provoked by people asserting opinions based on loose research...neither of them pays the other one's (or your) bills, and this is the internet...they'll both get over their differences and you'll be the recipient of good information and crowdsourced brainstorming.
Back in the crosshairs:
Just for grins, I looked up complete 3.9s on eBay, and found several for under a grand (comparable to the 5.2). You might be able to find better deals in your vicinity on craigslist. Don't be intimidated by the FI--it's a quantum leap forward from an off the shelf carb. Cold start drivability and mileage are significantly improved by comparison, and the accessory packaging tidies up the engine bay compared to the V belt arrangements. If I had it to do over again, I'd have pulled all the accessories for my 5.2 swap (my longblock was free to me, but it was just the naked long block--no accessories, so I used my existing parts which had it's own challenges)...and I may yet go that direction with assistance from magnum for convenience sake.
My own experience with 3.9s:
Although I've never built one or owned one, I have driven many. Even in a Dakota, they provide plenty of get up and go, and will feel like a mild V8 when you put a manual trans behind it, and will have less weight bias over the front wheels so it'll feel a little lighter up front. All the ones I've driven had well over 150K miles on the clock and still ran without indication of mechanical issues. Prices for a reman'd unit are a little higher than a 5.2, which is kinda weird as I think they both occupied a similar market share of the installed platforms, but even then, they are still available and just as easily maintained as any LA or magnum. If you went to the extent of rebuilding one with good parts it would easily last another 150K or more miles.