I've had my '87 RRC for about 10 years. First vehicle with a back seat I ever owned (the Baja Bug in college doesn't count, took the back seat out, same thing with my 'B-GT rally car). My truck has some 300k on it, upgraded to a 3.9 many years ago. Lost a transmission, my fault, didn't adjust a worn linkage. Front axle was replaced with a freshened up unit from a lower mileage parts truck. Rear axle and t-case are original.
My rules to live by with a Rangie:
1) Don't skimp on critical parts -- that aftermarket water pump will leak in 6 months -- but don't be afraid to upgrade when necessary
2) EVERYTHING ignition related is critical. Cap. Rotor. Wires. I think it'd be cheaper to convert to diesel over the life of a Rover V8 powered machine just to save the tune-up costs!
3) Change oil religiously. I've taken apart many Rover V8 engines (we've got the Rangie, a Disco, a TR-8, and an MGB V8, yes, I know, I have issues) They don't like to be neglected.
4) A little bit of PM goes a long way. For instance I use contact cleaner on the window switches, all my windows still go up and down. Dielectric grease, loctite, and anti-seize are your friends (in the proper places).
5) Don't let an idiot work on your truck. Better yet, learn to work on your own truck, you should care enough to do it right. I've done almost all my own maintenance. (Edited to add) You really do need a mechanic you can fully trust.
6) Learn to use an electronic multimeter.
7) You don't need an engineering degree to own/maintain a Rangie, but it helps.
Now keep in mind my truck isn't a Rubicon rig. A mild lift and other minor mods gives me a truck that can take the family on moderate trails and to the camping areas we care to visit but is still (yes still) a daily driver.
Maybe I've just been lucky, as I've seen proof of the horror stories. As much as I love my Rangie, and as many miles as it has on it, it can be frustrating...for instance the early US market trucks like mine had a horrible speedo design...I went through three of them before I upgraded to a later instrument cluster with the electronic speedo (uses the existing signal to the ECU). That is one nice thing about these trucks for the tinkerer type -- there are so many interchangeable parts across the years and some things Rover improved and others went to junk -- you can pick and choose the best parts from various years. Perhaps not the ideal path though for a "I'm used to a reliable Toyota and think Rovers look cool" guy.