Regarding the recent link in in SurvivalBlog to the articles on Converting a 1973-1991 Suburban to Cummins diesel engine, I have experience with the B and ISB series Cummins engines in several applications and believe they are fine powerplants. However, this swap IS an electronic engine and transmission, as described. And it is not necessarily something easily fixable in the kind of situation you envision.
I would suggest that a mechanical engine (which does include the earlier 12-valve B Cummins sixes and its four cylinder sibling the 4BT) and a manual transmission might be more suitable.
Several possibilities exist for this size of vehicle. I am sort of partial to the old Series 53 Detroit Diesel, all mechanical, simple unit injectors, nearly idiot proof. That’s why these two cycle Detroits went into so many LTL day cab trucks: union drivers couldn’t wreck them.
If you don’t really need this big a vehicle, I would look at some of the smaller Japanese and German (Mercedes) engines with Bosch style injection pumps. These engines are in many, many small industrial machines, gensets, etc. so parts are available. They are not high horsepower but they are all mechanical and generally very robust. isuzu, Mitsubishi, Nissan all have some great choices. With Mercedes you are looking at the OM 616 and 617. They are lower horsepower, very reliable units. There are some all mechanical VM Cento engines out there as well. Parts support isn’t quite as extensive but is available and they are quite robust, especially the six cylinder inline that went into FedEx and Airborne package delivery trucks for years. This engine is also widely used in marine sport boating applications and was installed in Jaguar cars in Germany by a tuner company with good results. – Roger R.