Water Pumps:Boy, I've done this job a lot. It seems that every time you let a rover sit for more than a year and then start it -- the pump seal tears. Drip, drip, drip from the little hole on the bottom of the shaft housing. I have yet to experience problems with the bearings -- only the seals.
Water pumps can be rebuilt but it requires a press -- in most cases depending on your time and your shop equipment, it is easier and more time effective to just buy a new one. After market's start at about $80 and go up for real Rover parts. Be careful of the cheaper ones -- they work fine but I recently had a problem with having to grind off some material at the top of one to get it to fit around the thermostat housing "bump" on the engine head.
The radiator does not have to be removed, but I suggest it. Removal is not actually that hard, just a lot of bolts, and it makes the job a whole lot easier to have more room and to be able to reach through the grill hole. It is also an excellent time to have your radiator flushed and that cracked mounting bracket re-soldered on. Flushing and repair can run you anywhere from $30 - $100 depending on where you live. They often paint it for free!
I have gotten into the habit of doing the alternator conversion while I'm at it and sometimes I even throw in a new thermostat. Once the radiator, fan cowling, pump, and belt are removed, the alternator becomes a snap. (See Roo's Delco Alternator Conversion)
The worst part of the job is the fear of cracking off those small 1/4" course thread bolts in the engine block. I twisted off the head on one of the top ones with Little car. I was luckily able to heat it up with a torch, unstick it, and grab the head with a vice grips. Success! Depending on you optimism you may want to order some additional small bolts and a helicoil kit?
Check List: Don't forget to buy the following beside the water pump
1. Seals and spray gasket sealant (or RTV, whatever your sealing prerogative).
2. New Fan Belt? Depending on the condition of the old one.
3. All 3 replacement hoses. (You will want to kill yourself if you forget to buy that critical center straight hose that goes between the pump housing and the engine.)
4. Hose clamps if they look sketchy.
5. New radiator cap (the seals are often trashed and you need the low pressure variety?)
6. Paint for the unpainted water pumps. Paint for the fan cowling etc.?
7. Anti-Seize thread compound to make the job easier the next time.