Sounds like this one was able to sneak in before the true 25 year import and hence the seller can ask far more than most would envision paying... and may get it too. As for whether or not it is worth it, all perspective. If one were to buy a clean FJ/FZJ80, convert it to diesel using a half-cut HDJ (or even HZJ), you could easily hit a similar number by the time it is said and done. One could do the work themselves and be into it half that amount but you can't compare buying to building as this rig is ready to head out on adventure tomorrow... not in a couple of years.
As for the HDJ80, I've motored around in a few... pretty dang cool but not a rocket ship either. Obviously they are going to feel peppier than a US spec 3FE/1FZFE powered setup and have a far better fuel range as well.