Which engone swap to do??

As soon as I get the body drop and bags done on the square body I'm going to start on the next part of it. The old lady said either big rig wheels or an engine swap but not both at the same time lol. So I'm leaning toward the engine swap first to make the truck a little easier on the wallet to drive.
The real decision to be made is which engine to swap in. Whatever i go with has to be economical to do the swap on and to drive. It also has to be a diesel. So far I'm thinking about an older Cummins 6bt 12 Valve all mechanical engine. To do that I think it's going to be cheaper and easier to just buy an old dodge truck and have everything I need there on the truck.
The other option is to swap in a Chevy 6.5L turbo diesel. Also with this option I'd probably just buy an entire old truck and have everything at the ready.
I'm not looking for a power house or some turned up stump puller. Just something reliable, cheap to operate, and fairly cheap to do the swap.

Any input, thoughts, or maybe something I haven't thought about??
Also the truck this is going in ,is the truck in my sig.

I just bought me a new truck this week....it has a 93 model 12 valve in it....same truck you have but its a SRW.... till next weekend anyway....so far im in love with it....its no speed demon but i put a 8k lb fuel tank behind it yesterday and it didnt even slow it down.....and so far ive gotten well over 20 mpg...im alot more happy with it than my LS swap in my other dually

Oh yeah forgot to mention it in first post but a 12 valve aint gonna fit under stock hood bodied.....i seen a suburban guy is buildinf and they got it under stock hood bodied but im not sure how lol

Cummings 4bt should fit

This is prob obvious as hell, but I've seen a ton of 6.2s out there fairly decent prices. There's a buy here in SD that has a 88 Dually with a 6.2 and a banks Turbo, he wants 2300$ for it. So u ha e all u need. U won't need to do much Fab work(easy on wallet) and u will have all the fuel lines and full set up u will need. I'm sure u may know but if not, u Will ha e to change the entire fuel system when u go from gas to diesel. So I think u should go with a whole truck if u can find it local. Cause if u try to piece it all together it will cost a pretty penny. Hope this helps and good luck! I wanted to Do a diesel swap but I'm just sticking with fuel. I'd like to get a stroked 383 I'm looking at one this week. We will see.

im in favor of the 4bt cummins. if you can aford it.. they are more expensive than a 6bt... (9 times out of 10)

im cheap, so i went with a 6.5 chevy diesel with all the accesories from a 6.2... but my engine guy told me not to sell the small block 350 i already have installed because i would eventually have to use it again....lol

Dead set on diesel?

If you want cheap and reliable, it's hard to beat a TBI 454. Diesels are great, until they break down. then it's not so cheap. 454's are pretty ubiquitous and parts are plentiful. Fuel injection will give you decent mileage, too.

Just my .02

I get about 9 mpg out of my TBI 454....I hear the later model truck do pretty good- (13-15)

^^^Sumtingwong

Shit, Man, I got 10 with my worn out Quadrajet.

Dude is already a TBI 454 so there's no swap for him there. but an overdrive transmission would be a big improvement.

Campy - you'd be surprised, often there's not much comparison on MPG's between a TBI engine and Quadrajet engine if everything else is identical. The TBI definitely improved drivability over a full range of atmospheric/climate conditions but MPG-wise, someone really good with Q-jet tuning (not common but they're out there) can often squeak slightly more MPG's out of the carb.

Richard