they really don't have to be cut down that much, I have just ground a slight angle on the end and that's sufficient.
And don't have to much (or any) paint on the brake drum as this can lead to a loosing of the splined hubs (or wheels) due to heat affecting the paint.
Also I am running (I think!) cortina MK2 wheel nuts as they fit, clear the rear of the wheel and have a good head (steady) to get plenty of purchase when tightening.
Adding a thin (5mm) wheel spacer avoids the need to modify the studs at all and allows you to revert to regular wheels over the winter.
I don't understand why they didn't make the adaptor flange a bit beefier so that it didn't need special studs. The flange has been known to fail if pushed a bit too hard, and you could then use proper wheelnuts as well. (Ian Mcdonald broke one on the rear end at Le Mans and the errant wheel caused no end of damage)
oooooooh, and then there's the issue of the studs!
The original studs (if you're unfortunate enough to still have them fitted) have a nasty tendency to pull out/rotate in the flange.
Most people by now ( I sincerely hope) have drilled/machined these out and replaced with TR6 (I think) which are far better suited to the pressures administered by heavy right footed enthusiasts.....