FJ60 is a good front axle. That being said the answer you are looking for is yes and no.
An '84 FJ60 will have 3.73 gears from the factory so unless it has been regeared it won't match your '85 mini that probably has 4.10s...
The mini-truck springs do not have to be outboard to fit the FJ60 housing but the housing will need to be SOA'd to fit. You may even want to do a cut-n-turn to point the pinion at the T-case and set your desired caster.
If you go this route you may also want to grab the FJ rear axle to build a hybrid rear end with the big cruiser pumpkin to match the front.
The FJ60 axles are over 2" wider than the mini so that will work to your advantage and you gain that width without the added scrub caused by spacers.
You will also gain the larger vented rotors and calipers...
...and just so you know, an FJ62 axle will have 4.11s and 10° higher pinion angle than an FJ60, which saves you a bit of work. FJ62s also have a gusset on the bottom of the housing.
