80 diffs are all 4.10. I daily mine on 35s with a 5-speed and 4.10s without issue. It is lighter than most, though. IMO, 35s are good compromise for a rig that sees a lot of highway miles but is wheeled hard. For a dedicated wheeler, 37s or bigger are the way to go.
With the narrow frame and higher offset front diff, you will either need to outboard your springs or french perches into the housing like this guy did: who's running a fj80 front axle, and who wants to? - Page 41 - Pirate4x4.Com : 4x4 and Off-Road Forum
Or you could bite the bullet and link it. Either way, be sure to get the axle very secure before welding or it will warp and leak.
With the narrow frame and higher offset front diff, you will either need to outboard your springs or french perches into the housing like this guy did: who's running a fj80 front axle, and who wants to? - Page 41 - Pirate4x4.Com : 4x4 and Off-Road Forum
Or you could bite the bullet and link it. Either way, be sure to get the axle very secure before welding or it will warp and leak.