Howdy Graeme,
Just finished lining mine by hand in December on a rattle can restoration of my recently completed Shadow. Porsche Guards Red (pre-89) using the factory code provided by Glasurit/BASF is the best match I've found to the original rim I used as a reference. Though all know this here, these were single stage paints, thus subject to discoloration by solvents/petroleum based products over time. You may find the lining on an original rear rim appearing almost burgandy or Indian red, thus, my reference was an unspoiled 20 inch front.
This lining is applied abutting the black center - not over it - and thus being somewhat transparent subject to "reflect", so to speak, the sheen of the plating under it as it's applied directly on this surface with no primers.
That said, original rims were primarily polished where the chrome was exposed, appearing matt - like hard industrial chrome where not - I was not able to impress this nuance on the plater who did the rims to a jewel like finsh on my Rap in the signature below. Though my black laid down nicely, striping over that surface deviated so far from standard in appearance - almost like a red version of a yellow safety vest, I stripped it all off and left them bare.