Hi Gordon,
you can get original stereos, e.g. Blaupunkts that were fitted as standard, but very expensive.
i had the original radio cassette in my 3.2 garage queen show car which I'd put in when doing the club concours and sure scored points, but to be honest, was pretty crap compared to modern alternatives.
i had a loom conversion harness and switched it out for a black Sony radio cd for the rest of the time.
As Steve says the Porsche classic is the dogs, looks good etc, but not cheap. Depends what you want.
you can get non working original units cheap for asthetics, and some people do this and have a concealed iPod type unit in the glove box for use.
sat nav wise, best to use phone with something like Waze app.
the screen aerial is ok..ish.
loose the stick-0n job unless you want to retain the 80's yuppie look. My car still has the hard wired phone clues on the centre consol and in the bonnet area where you can see evidence of the mountings.
i guess these things do show a certain extent of originality, which I quite like in a way.
its great fun getting your first 3.2, Im envious.
regards
Graham