Read this thread before you pull the trigger on that particular Impulse:http://www.isuzone.org/forums/showthread.php?t=5631
The 2.6 swap CAN be done, but I don't think it is as simple as just dropping the 2.6 in.
Body parts for Impulses are scarce at best. Totally hit or miss. Pretty much every part that is Impulse only
is discontinued by Isuzu. Unless Isuzu has stock of it sitting somewhere on a shelf or in Japan, its pretty much gone. For example, I ordered a specific v-belt for my rebuild yesterday that is for Impulses with no a/c. I had the Isuzu part number, and when I called my Isuzu guy to order it, he said it is discontinued, but there was ONE LEFT
on the shelf in Ohio. I also got the LAST water inlet pipe in stock in the USA for the 2.0L turbo (87 specific). A bunch of other parts I ordered are on back order which means they have to come from Japan.
1st generation Trooper parts are a lot more plentiful for sure. I have ordered a lot for my 91 Trooper and a lot of it is back ordered, but it comes in eventually.
The sad truth that I have to swallow every day is that my 3 Isuzus are "extinct" and eventually parts will dry up for sure. Thankfully, my Trooper has the GM drivetrain, so all those parts are pretty easily obtained, and in my part of the country, Pick & Pull has Troopers regularly for body and interior parts. After my 3 vehicles are "done" I will become a serious part hoarder I think.
If it were me, I would be looking for a nice RUNNING JR Impulse to start on. That way you know you just need to do a refresh similar to what I am doing.
Just remember this: That car is being sold for a reason
. That said, it would be really cool to see another JR build on here!!!