"Amateur built vehicle", if you'd prefer. Clearly, the vast majority of the underbody structure of the car is one you yourself have designed and built, rather than the one that came out of the factory. Mechanically it bears no resemblance whatsoever to a Minor. What the DVLA think of it is up to them - I'm actually quite surprised you've been able to avoid a Q-plate and SVA/IVA. You'll note that nowhere did I dispute the owner's right to modify the car. I'm concerned with how best to preserve the Minor, and I don't think that degree of irreversible modification really counts as preservation. You are of course right that breaking up easily restorable cars is even more inimical to that objective, and I've expressed that viewpoint before.KIT CAR!!!!! KIT CAR? that's offensive and insulting! there is absolutely nothing KIT about it!
Chris' car is one I like a great deal. It very clearly is a Minor as it retains the original bodyshell and structure, is still RWD, has an A-series engine, still has torsion bar front suspension with leaf-sprung live axle rear, I could go on. Also, I suspect that most or all of the modifications would be fairly easily reversible.
You'll also note that I said I'm not against all modifications. Until I sold off the bits, one of my cars had a 12G295 cylinder head, 997 Cooper cam, HIF38 carb, Metro rocker cover, K&N filter, etc. My other one has an alternator, stereo, radial tyres and cigarette lighter socket. Point is, these are all modifications that are unobtrusive, bolt-on, and very easy to get rid of (as I did in the former case). I even tried to buy a ropey B-Series engined Minor about 5 years ago. This is a bit more radical but could still most likely be reversed, and in addition uses 'period' mechanicals (the particular car I was after had been converted in the 70s). Probably a conversion I wouldn't undertake myself now, however, with the ready availability of cheap MGB GTs.