Point taken that a scrapyard bodge job would probably look very messy and I guess it would be hard to fix up the modern plastic dials or knobs in a discreet location. Not that I would personally bother...
For those who are more tollerant of 21st century technology

You make me sound like a technological luddite.... Seriously, I'm not adverse to a bit of modern technology in my car (I have a Clifford Immobiliser for example

) but I wouldn't like to see something which looked totally out of place.
I'm not bothered what the hidden bits look like. For the later cars you could have a flat metal frontplate painted matt black with a vertical lever which looks very similar to the original. However the lever could control the three blower speeds and the off position. Two further switches (perhaps of a similar flip style to the light /windscreen switches) could control the windscreen/car and fresh air/recirculated air options. Hot or cold water flow would continue to be selected via the original button under the glove box controlling the heater valve. That kind of discrete upgrade would have been most welcome this evening as I was driving through a snow shower with mist & ice forming on the screen....
It's a fact that a moggie with a well worn dynamo can barely cope with the lights, wipers & heater on for any amount of time. However I would guess that modern fans & motors would give a lot more oomph than the tired old 1960s efforts in our cars, so as long as the power drawn wasn't disproportionate then it would be a very worthwhile upgrade.
