I like the 12v 5.9's, but they are so **** popular you could find a mechanical DT466 for cheaper. More cubes, more robust engine, easy to find with air compressors, can be found stock up to 300 or so hp and the inline pump versions are just as easy to turn up as the 12v cummins.
this is all true stuff. though, it is worth mentioning that the dt466 is a full-size medium duty engine. dimensionally, it's as large as the multifuel, so it would likely be almost a 'bolt-in', physically speaking.
however, the dt466 usually uses an intercooler. also, the multifuel radiator will likely not keep up with the '466 - it may since you might never be able to make the '466 break a sweat. but, i want to bring these tow issues up as considerations - there isn't room for a larger radiator and intercooler under the 'A2 sheet metal.
medium duty engine by International, 466 cid. very popular, plentiful, very reliable, very 'horsepower friendly'.
What do you think of the DT360? Only because I have one of those. I was liking the idea of setting that into a bobber, someday....
the '360 is the little brother to the '466. this is about the exact same relationship as the 5.9 to the 8.3 liter Cummins. for all intents and purposes, it is exactly the same as the 5.9 Cummins as far as size, reliability, ease to work on, 'horsepower friendly', and ease to turn-up. in another forum, a gentleman just finished swapping one into a late model Super Duty; right now he's at about 500 rwhp and will be taking it to 600 very soon...... and just like the Cummins, this is all with basic fueling mods and on stock internals.
as was mentioned about the reputation, popularity, and lack of availability of the 5.9 Cummins, the DT360 is an over-looked treasure. use it!!!