I have something like that in the garage right now....
I happened upon a very nice 1996 LX450 chassis with only 107K miles on it and it had the E-locker option. I couldn't pass on it for the price, so I decided to build something out of it. The previous owner had pulled the low mile powertrain out to refresh a built high mileage 80-series. That left a big hole to fill. I decided to do a 2013 GM LC9 5.3 all-aluminum V8 with a 6L80 6-speed automatic transmission. To throw a curve ball in it I am using a Land Rover LT230 transfer case. It has a 1.22 high range and 3.32 low range which will allow me to keep the 4.10 gears in the axles. The powertrain was mounted high enough in the chassis so the belly is completely flat to the bottom of the frame. The engine, and body, have been moved back to pull some weight off the front axle along with provide a little more space for the larger tires.
The body is mostly custom. I started with a clean-ish FJ40 tub, I found in arizona, and promptly cut it in half. The FJ40s are a bit too wide in the hips for me, so I pie cut the floor and took the taper out of the body starting at the front of the door. This left me with a tub that is about 56" wide instead of over 63" wide. I will be making it into a FJ45-esk tub and hand making most of it. I am trying to keep the overall weight down so a lot of the body I am building will be aluminum. I am making a modular hard top along with 2pc hard doors that will have glass sliding windows. The bed will be a small 1940s-esk stepside unit also made mostly out of aluminum. The grill is going to change shape a little bit to make room for the tires when turning. The larger tires will go lock to lock on the factory steering stops, but the 'corner' below the headlight gets in the way.
This one is running a 40" tire ( and would just clear 42s). From what measurements I have been able to find, I never had a complete stock FJ40 to measure from, I don't think it will have more than maybe 1-2" of lift to fit the 40" tires with about 5-6" of uptravel.
It should be a fun little thing when its done.