Hi Chris, I certainly agree, you can't go scrapping Rover V8's these days, just not done. I had a similar problem last year where I couldn't achieve an even idle speed, did all the checks as you discribe and could find no fault (I have boyer brandsden electronic ignition on my V8, this still retains the points but only as a switch therefore very little power going through them) I have a multimeter to check dwell angle (points gap at 15 thou) etc and I noted that the dwell angle could change astonishingly over a short time, e.g. set it at 27 deg then after 10 miles or so it could be 20 deg or 30 deg ?? the problem was the moving plate in the dizzy, where the plate pivots on the small pin, the bush had worn so there was excessive play allowing the plate to move and therefore I couldn't maintain the correct dwell angle, so I fitted another moving plate which had no play at the bush and presto!! spot on idling, incredible the difference this has made to the car.
Regards DAV8
Dave