11630 MHs with black dials and grey registers feature in catalogues as early as 1977 though, albeit with orange rather than light grey highlights. My Carrera Twins, watches that were phased out at the end of 1981, both have serials beginning 391xxx so I'd agree with Jeff's date assessment - in fact, I'd probably lean more towards '78 than '79.

And if we look at the catalogue for 1978, we do see a 11630 MH in the same configuration as the one on the front of the 1982 brochure:

So, entirely correct in my opinion James, no mismatching dates/layouts or such like to worry about :)