The biggest concern is rust, more so when you can't see it and even worst when the main body consists of filler, cardboard or newspaper. So it's worth arming yourself with a magnet and using it to ensure all the problem areas consist of good steel and are not hiding the aforementioned bodged repair horrors.
I don't want to put you off, no not at all, because if you buy a good Mini, you'll be happy forever and ever. But buy a badly bodged Mini that fails it's MOT big time because it's literally held together with filler, cardboard and newspaper and you'll then hate it with a passion.
Exactly. I bought one on ebay which turned out to be a real rust bucket.
It's sitting in the garage now awaiting my welding 'skills'... because I could bodge fix it but that doesn't seem right?
I'm really impressed with the way in which you're researching this whole thing.
You're going to end up with a decent mini provided you keep this going and get the help of your local mini club.
And if you're careful, you'll probably have that same mini when you hang up your driving gloves in fifty years time!