Don't bother me with the facts; my mind is made up.
This thread is about possibilities of acquiring a 12HT stateside, not a debate about power trains. I happen to think a multi-fuel diesel would be easier to feed in the inevitable future civil breakdown.
As a guy who has done a few Toyota diesel conversions, and daily drives them (over 340,000 miles on one), I'll give you my 2 cents....
When you find a good deal, is when you will know how to get a 12HT. Or a 1HZ, or 1HD-T. (those are the engines I would personally be looking for if I were in your shoes). All of them have plusses, and all of them have drawbacks. But all of them would be awesome in a 60 series.
I had no idea how to get a 1HZ, without paying a huge sum to SOR or something. ....until a running 1HZ sort of fell into my lap for very, very little money. The next two 1HZs I got because I knew someone who was trying to get rid of them, and I had some cash to throw at them. The 12HT wasn't even on my radar, until i saw it sitting in a container and I knew they were trying to sell stuff. I bought it with absolutely no plan to use it, but I knew it was a great deal, so I snatched it up. (and then we decided to keep it for Dad's 60)
If you are serious, you'll find something that works for you. My advice, would be to keep your mind open, because if a good deal on a 12HT comes up, you'll want that. Or if a smoking deal on a 1HZ presents itself, then go that route, etc...
That said, if your supreme primary concern is in your post apocalyptic "bug out" scenario, then you should limit your search to the 1HZ. Indirect injection diesels are MUCH more tolerant of multi-fuel issues than direct injection. Not saying multi fuel won't work in a direct injected engine, but it'll be more finicky. And you could carry the spare parts for a 1HZ a lot easier, since they were at least sold in north america (granted, not for highway use, but there are plenty of 1HZs in mines and things here).
Dan