Replace your thermostat.
You all are in good company. My 03 has had a slow leak for the last two years off and on. Was a TB gasket and then the TB heater hose at the intake and now it's bad enough to see, front cover and intake 90% and maybe 10% heads.. All external, no water oil mixing and no burning and NO overheating but is dripping pretty good now from the front and running across the oil pan front to back....Coolant has always been changed with all other fluids by the book or earlier as I have with my 98... My 98 has 180k no problems anywhere ever and the 03 just clicked over 100k.... I will be tackling the heads this weekend as well as replacing the front cover gasket and inspecting the oil pump dowel since mine falls within the vin range for the faulty pin causing oil pump failure.....Nice huh..... I saw someone write about other's head gaskets lasting for hundreds of thousands of miles and that is correct, but there are tons that do not such as the famous GM 2.8 Ford 3.8 and Toyota 3.0L.... I think the GM 2.8 is what made instant stop leak products famous LOL..... Yes it sucks that our engines are 30+ years old and they still can't figure out how to make them leak free but the benefits of Rover ownership outweigh the problems...I do not know what else I would drive that does all the things our Rover's do...I used half of the 32 oz. bottle called Blue Devil "Mechanic Approved".
Man I would give a hand butt your all the way out there in PA, I like working on cars, bikes almost everything, but dont worry man your Rover probably will run like new again.So I guess that tomorrow I will start flushing and flushing.....