FJ40's are incredible. So well thought out and of course, they, in the beginning copied Willys but went on to be on another level. The inline 6 is as smooth as butter and wonderful low end. Not all parts are available but most. Many parts are still made by Toyota but be prepared to pay as they are not cheap. That is why many have dropped Chebbi engines in them starting in the early sixties.
I like the inline 6 so I had no intention of changing things out.