Thanks so much for these replies - really very kind of you all to offer advice.
No
definitive answer though I guess. Short of getting my hands on a manual for a 'Carat' I think I'll never know. (FYI, I had read that the 'Carat's were only made 1990 and 1991 - and yes, they're the 'posh' models.)
Re changing the garage door, I was really hoping to avoid it, but it's looking like that might have to be the way to go - I've fallen hook, line and sinker for these vans.
Just to confuse issues further, we've looked at a caravelle tin-top that's up for sale - it's been lowered (don't know by how much), and the owner says the height is 1860mm. So close!! I wonder how it manages to come in at that height though..?
Thanks again to all of you. Very much appreciated. It was my first ever forum post, (on any website!), so I was delighted to get replies.
Kx