What a brilliant story!
You definitely did the right thing in rescuing the shell, kudos for you for turning down £20,000 as well, I've got to totally respect you for that and at the end of the day money isn't everything..... happiness is!
For me personally I would try to restore it back to how it would have come from the factory, that just my piece of advise. Just remember that the worse vice is advise!!
To me it's a piece of metal at the mo, it's only until it becomes a true complete mini that you can drive and have fun with it and then it becomes alive!!
I'm very lucky to own the Miniworld Project 45 car. She gets driven and I bloody well enjoy it! Very soon when we get some decent weather and I've put a few more miles on the Engine I'm going to open her up properly over mountain. I fully intend on getting the speedo well into the 3 figure territory! That doesn't mean that I'm not going to look after her properly but it's what she was built for! I've already modded her by making up some stub stacks (try buying one for a DCOE 38) and adding an air filter instead of having the tea strainer filters. Next I'm going to change the dash (it will look very cool but also retro and classy), and then I'm happy!
What I'm getting at is remember that this is now your car and ultimately you can do whatever you want to it. I think so far you are doing the right thing, just follow your gut and do what you want to.
Oh and enjoy it!!!