Ignoring the location (about 60 miles away!) of the nearest wheel refinisher to me Mark, it would get rid of the last bits of paint but that's not really the problem.
Those gouges have got me thinking. I'm assuming/guessing that there was some kind of filler in them under the first coat of primer which, as i've discovered, is hard as bell-flint.
It makes me wonder what i'll find under the primer that refuses to shift - will there be other casting faults that then need refilling with some sort of filler?
If so, all i will have achieved by removing those last traces of primer is making more work for myself and having to paint the wheels anyway, instead of having the fronts mirror polished and lacquered.
As this is the spare, it wasn't quite so critical if things didn't go according to plan or to put it bluntly, if i screwed it up. However, what i've found is that while the wheels looked nice with the original paint on, they were originally rough-cast, etch primed, spray filled, flatted then primed, 2 coats of silver and at least one of lacquer then baked at 140C to harden the paint.
It worked well, after all, the wheels are 30+ years old and when clean, still look pretty good.
This is really what put the idea in my head to mirror polish them. It seems there was a large dose of "smoke and mirrors" by the wheel manufacturer/Volvo originally though.
It leaves me in a quandary. I've spent about 2-3 weeks, on and off with about an hour a day doing a bit here and a bit there and most of that has been stripping back the original paint.
With what i've found with the gouges and the last reluctant bits of primer, i'm seriously considering just repainting it and when i come to do the other 4, just sand them down enough to key the surface, repair any kerb rash with filler, prime and paint then lacquer them.