Yes, very valid point made by Dan on keeping it standard....
Im running DeCarbon shocks and scrap-iron racing springs on the 90 in the UK so it handles better....than a 2cv (just).....would I use them overland ?.......nope....
Id replace the radiator and hoses (

...I see you have already) as a matter of course with a 97 - corrogations will find any weak areas in the rad - and rover rads have a habit of rusting out around the bottom, where water/mud gets trapped around the crap drainage holes in the mounting frame.
Its all pretty much been covered by the guys.....water pump, alternator, wheel bearings/seals (and a few extra locking tabs), prop shaft UJs for sure, head gasket as eightpot mentions, plus all those 'lil bits n pieces.
pack in as many fuel/oil filters as you can cram in....they can be quite expensive....at one place in Accra they wanted £15 for one fuel filter (last time I was there)- plus if you have bought them and wrapped them in clingfilm in the UK, then you know they are not full of dust/sand !!!
* Looking at your website, seems everything has been covered - a couple of things I can think of after a few

s are:
a fine mesh grill infront/behind the black plastic grill is good for keeping locusts/bugs and grass seeds out of rad, a swingaway pulley block will make the winch much more versatile - and take at least 1 inner tube with your puncture repair kit- just in case you lose a sidewall - get a local to patch/sew it up and put a tube in and at least you can use it as an emergency spare on the back end.
I also use the small black 5 litre diesel cans for my oils -2x Engine oil /EP90/ATF - they are very tough and dont leak, just mark them with tippex.
I do an oil change every 5000km, check wheel bearings and fresh grease in those UJs, if you go West Africa way, consider doing a couple of interim fuel filter changes.
...and if you go through Ghana, stop at Brenu Beach and enjoy a few 'Star'

s !!!
Have a good one
Cheers
Gipper