OD1 Lol I did however sand the cones and made the surface smoother, and that was the day I got them.
As the Celestion distributor for SA I have to say that this practice is definitely not recommended and will void the warranty. The same applies to other practices such as treating the cone or surrounds with solvents, physically damaging or "ageing" the suspension or for that matter hitting things with a hammer.
If you really have to have the "original vintage" tone the rather buy a genuine vintage cab or try to source the now discontinued Heritage Greenback speakers.