I have mine behind my turbo'd 1HZ, 275mm flywheel. The only thing I had to do is after about a year, year and a half, I needed to put in a HD clutch as it was slipping. Once it started slipping in 3rd I put the HD clutch in. 1 month in, and the clutch is fully broken in (no more noise) and it...
The newer HD 70's have the R151 behind the 1HZ (I have a 2002 HZJ76 with one).
Maybe get measurements of the bell housing, that might be the only way to tell for sure. Does the bell housing have a part/serial number on it anywhere?
If it came out of a heavy duty 70, it was likely behind a 1HZ. Without any info on it, mileage, etc you could probably get $1500US for it with the transfer case if it is in good condition.