Nice. Makes sense with the barn doors and no flares.
As far as maintenance suggestions, I would look at the usual baseline stuff - timing belt, water pump, all fluids, fuel filter, replace rubber coolant and fuel hoses. I found that the heater valve on my '97 was crumbling and needed to be replaced ASAP so I did a decent overhaul on the coolant system with all new hoses, radiator, heater valve.
EGT gauge if you don't have one yet.
Maybe you already know all this so I apologize for rambling but here's some info I would have appreciated when I first picked up a diesel 80:
There's a separate section just for diesel cruisers specifically where you can find answers to most questions diesel-related -
Diesel Tech / 24 volts - https://forum.ih8mud.com/forums/diesel-tech-24-volts.24/
Lots of info in there for upgraded airboxes, turbos, tuning, fuel pumps, injectors, you name it
There's also a separate JDM/Diesel classifieds section -
Classifieds: Diesel & JDM - https://forum.ih8mud.com/forums/classifieds-diesel-jdm.92/
I buy most of my parts from Partsouq, Cruiser Outfitters or Amayama.
Partsouq is in Dubai but shipping can be surprisingly fast. The parts charts are especially helpful
Cruiser Outfitters AKA Cruiserteq is in Utah and has amazing customer service.
Amayama is in Japan and has a lot of parts that can't be found in stock anywhere else.
Australia also has a huge cruiser scene and I buy stuff from there like my exhaust, airbox, floor mats, (random RHD stuff for me), future turbo upgrade...
The 80 Series chassis is 90-95% the same across models and regions, from suspension to brakes and transfer case which is nice because you can find a lot of parts in the US. the 1HZ is cool because it's still in production today and you can buy just about anything you want for the engine new.
I use a combination of the US 80 series FSM for chassis, body and drivetrain, the 1HD-FT FSM for engine stuff and the HDJ81 EWD for electronics. All of that I believe can be found in the resource section -
Resources - https://forum.ih8mud.com/resources/
That's all off the top of my head. You're gonna love it. Jealous of the 5-speed.