MorganMike, welcome to TM. There are a number of specialist around the UK who can rebuild your Morgan. Your are correct that Mr Rutter will do all the jobs that your MOG requires. A person who can repair/replace your leather work is a chat who lives near the factory. His name is Dave Kriesel. He can also put you in touch with someone who can rebuild you a body if you need it. Currently the prices for old MOGs and Classic cars in general have dropped, a buyers market. If i was to buy a older MOG today it would either be a Rover Plus 8 or a Ford Kent Crossflow 4/4. The reason is both engines are easy to work on and you can get parts very easy. Ford sold 10 million crossflow engines in various cars over the years. As you state you already have a Plus 8 so Mr Rutter will exchange it for you for another MOG if that the route you decide to take. But since you have a 1970s Plus 8 with paperwork from Peter Morgan i would get it rebuilt. Power steering can be put in.
Like others on the site have said, it will be interesting following the path that your next Morgan adventure takes you!