This is an era about which I can offer almost zero advice, but, one thing you've said is something I can advise on: You are very, very, very unlikely to have to worry about "too many" miles on virtually any Rolls-Royce.
The thing that has killed more Rolls-Royce and Bentley cars across the decades is disuse. Electromechanical and internal combustion engine parts age far less gracefully when they sit and sit and sit than they do when they are used for daily transportation. And maintenance gets deferred, significantly, when a car is a garage queen that gets taken out once or twice a year, if that.
When I was still a member of the RROC (US) one of the members who owned a service facility in California had a Bentley T1 with over 500K miles on it, and still going strong, very strong, and a part of that is the result of it having been frequently used and well maintained.
Ultra-low mileage, regardless of the marque involved, should be considered a red flag, not a virtue. And as someone who purchased two SY era cars, one with about 80K on it and the other with about 23K over the same number of years, I can tell you that the one with 80K was the far more reliable of the two.