Diesel will pay in the long run.................BEEN THERE
I am going to use a 2 stroke Detroit in my K-20 WHEN I do my next conversion. I haven't been able to find the right 4-53 or 4-71 at the right price yet and that is the only hold up. They are very noisy, but are tough as nails, run cheap, and you can put the real Jake Brake on them and that is worth its weight in gold if you ask me. I drove a few Jimmy powered trucks growing up and I like them.............Slam your hand in the door jam and drive them ticked off all day and they'll hike a load over the road in short order. I am going to tweak mine and add rpms, 92 series injectors and some other mod's............She'll be a screamer no doubt.
A 6BT(AKA 5.9) is a great engine to use as well, a 4BT(4 cylinder version of the 6bt) would work possibly if you geared it right for what your gonna be doing with the vehicle.
I'd like to try using a 354 Perkins(It has been done by a few), DT-414 International..........They make awesome torque and are plentiful and parts are cheap, a Deere 404.............And if it was possible a 466 Deere would be awesome.
I got a 6AT3.4 Cummins in one of mine............For only being a whimp(Small compared to a 5.9) it blew the doors of the 454 I had in one of my other ones on the hills here in PA...........I like diesel for these main reasons.
-Longevity, they'll go FOREVER between OH's.........Unlike a V-8 gasser which doesn't get anywhere close
-Simplicity, face it, not to much to go wrong on a mechanically injected diesel
-Fuel Economy.........Yeah it is better, although price differences is making that less of a factor.
-A biggie for me.........Its different from 97.7% of everyone else
-Another big one for me.............Torque on the low end out the rear, unlike a gasser, you can pull a good diesel down and it'll take ALOT before it gives up.
About the only thing I don't like is running one in the cold of winter........Gelling fuel and getting one running can be a bear when it is COLD out. Fuel conditioner and block heaters(Or tank heaters) can make these problems relatively small.
Whether it is for you or not you'll have to decide. I don't even have my '71 Completed 100% yet and it has paid for itself...........Other than driveline reliablity I am very happy with it, I plain on swapping in a HD ZF-6spd with an oil cooler along with a heavier driveling to end that headache.
I kept my expenses small with my conversion, I saved alot by using a stock GM transmission/driveline that held up behind anything GM made............Don't make the same mistake I did, they DON'T behind a real diesel. Ok, ok, they might if you didn't load the heck out of the truck, and let the engine peak out on the torque curve
something has to give..........