Welcome, they are great fun and quirky car's. I have had the Double Dim unit and it is fine, I sold my one a few days ago, I am not sure it looked great in the car but then that is a personal choice. There is a new android unit that some of the 75 & ZT people have. That has more toys, but more importantly looks more like the BMW E46 unit that I think suits the car better.

Have a look on here http://www.the75andztclub.co.uk/forum/ under the ICE section and then the Double Dim Units. Sean is the man who supply's them and is the seller you listed on ebay.

If anywhere close-ish to the Midlands visit Nick & Jean at Austin Garages, sure all the rest of the guys will tell you, he knows every inch of the 260 and is worth it just for a once over as well as any work you need.

Dominic