86 is a great year Toyota truck, unfortunately you wont find many aftermarket parts for them these days.
Heres a few manufacturers still making parts, beware they wont be cheap!!
https://www.allprooffroad.com/
http://www.off-road.com/trucks-4x4/tech/parts-suppliers-19411.html
This really might be a great time to teach him about fabricating your own parts, and a great excuse for you to buy those new tools you've always wanted.
Roll Bars are almost non-existant now days, most go with in cab cages, roll bars as they used to be known are now called "Light Bars" since their built so flimsy they wouldnt hold-up in a roll over and mfgrs dont want to get sued.
I've only seen a few trucks of that yr/model with belly pans and they were all custom made.
For a push bar I'd probably look at local swap meets and flea markets then modify it to fit.
Nerf Bars are still available but for real durability I'd look at sliders or rock bars, theres a few mfgrs that sell them but if you search the internet you'll probably be able to find plans to build your own, I've made more than a few pairs, the most important items needed are the truck to fit them on, tube stock (I prefer round 2" cold rolled) a tube bender, welder (mig, stick, or gas will work fine, mig is quickest though) chop saw, tape measure, angle finder, and a few other assorted tools.
Dont know if you have a Tractor Supply near by but they have a great extruded aluminium tool box that fits in the back of these trucks.
http://www.tractorsupply.com/tracto...d-aluminum-crossover-truck-box-silver-1091800
ARB makes probably the best locker out for the Toyota r/r axle but it isnt cheap and you gotta add the cost of an air compressor, while the air compressor is worht its weight in gold when it comes time to air up the tires (the mfgr also thinks it's worht its weight in gold) I have a hard time paying their asking prices.
You could go with a Lincoln Locker but that brings about it's own set of issues like no selectability which increases tire wear, on the road it can have quirky handling issues, and the rear diff pinion gets worn (most times broken) quicker.
The 22R is a perfect engine for a little mud runner as it doesnt mind putting out high RPM's all day long, a great addition to boost its performance is a header, performance wires/ignition module/cap/rotor, and a webber carb, side draft models work real good but any model webber is an improvement over the factory Mikuni (its not a bad carb the webber just does better).
Swapping the frt and r/r springs for a set of F/S Chevy 63" springs off a mid 90's Chevy will give the suspension great flex and a lot better ride, also a few inch's of lift for so you can stick 33-35" tires under without trimming or body lifts.
Did I mention I've had 9 of these trucks over the years, the only reason I ever got rid of any of them was because I flat wore them out off-roading, they went to the scrappers when I got done with them, their great off-road trucks and can take a beating more than most trucks,