I was able to take some measurements off of a stock FJ40 yesterday to try and dial in bib placement. The whole body swap is really based on the location of the front axle under the fenders. On the stock FJ40, from the center of the axle to the front of the bib is only 13"! On my UZJ project, I moved the front axle forward about 1.5", so that number could be reduced even more.
I went home and started looking at the 80. I
really didn't want to move the engine and transmission location. I'm trying to go on the path of least resistance this time. With the measurements I took, I'd have to move the drivetrain back 10.5". That makes room for AC condenser, radiator, mechanical fan, shroud, and spacing between everything. I'd have to build new engine mounts, new transmission mounts, new brake lines, and driveshafts, move my sway bar, and I'm sure a few other things I'd rather not do. So, I'm going to leave everything where it is and do a rear mounted radiator and AC condenser. I don't plan on using the bed for anything, other than sitting on the tailgate when we stop for a beer.
I put a red line 13" in front of the center line of the axle. This represents the front of the bib on a 40. You can see the steering gearbox and crank pulley are 2" behind that line. The bib is 1.5" thick, so that would leave about 1/2" of clearance if I put the bib in the factory location and leave everything else where it is.
They are different sized tires on the 40 and 80, so that will change the perception a bit when looking at those lines.
Now that I know where the bib will be, I can mount the body on the frame according to the length of the hood. I can also figure out how much I can stretch the cab and come up with an appropriate bed length.