Oh yes my favourite classic too. I owned many souped up specials including a MkII with a modded 1293 motor that was so quick it only lasted 10days before I frontended it head on into a Sierra overtaking when I should of been a little more patient.
Of all the minis I owned the one I loved the most was my brand new Mini30 I picked up on Aug 1st '89. I'd covered the 1000 careful miles of running in in a week and the dealer was shocked when I booked in for the free service. They had to replace the synchro between 1 and 2 as it would grind going up the box. I covered 175,000 miles in it by the end and opnce the year warranty was up I spent every penny on mods. Back then it wasnt so common to see minis on 13 inch wheels - mine was on colour coded 4 spoke revolutions to match the paint I could stretch a set of 175*50 13'' Yokohamas to 3000 miles before I had to reshod them.
A list of mods : Aldon distruibutor, Stage 3 unleaded head, lcb manifold,RC40 exhaust, re-needled carb copper head gasket ultimate engine stabiliser, second tank, kenwood hifi - I could go on. The 30th birthday party Rover held at Silverstone was a blast!!!
After resting at my grans for a few years awaiting a restoration I flogged it for £120. The garage was that damp when we pulled it out onto a lorry it looked like it had a fluffy steering wheel cover - it was mould on the leather, the seats were similar.
Sad I know. I miss it lots.
I'm familiar with the z'cars bike engined conversion - I just wish I had a garage and more time on my hands.