Hello John,
As you’re not a stickler for originality, as others have said, do whatever pleases you the most. But on the point of originality, the Red colour of you diff housing is not correct for an S3; it is black.
With earlier cars (S1/S2) having Red Oxide colour on the diff housing, their covers were painted black.
Although there is some documentation showing that Black over a Red Oxide Gliptone paint was ceased at some point, I’ve never seen an S3 car (that was unmolested) with anything other than a Black diff housing. Most S1/S2 cars I’ve seen that are truly original also show clear evidence of Black over Red Oxide colour.
Regards,
Bill