This is interesting. I'm a newb, and I'm positioned on the wrong side of the ocean for parts availability, but I think this would be pretty amazing on my grey market Jap Spec re-vinned 1976/96 Mini.
Is it possible to fit a M45 within the confines of the bonnet and keep the A/C fitted? I would imagine so, as the A/C is on the front and the M45 appears to go on the top/rear. But in practice...
Also, turning the A/C off might just have the same effect as installing a supercharger.