Dear Paul, thanks for taking your time for this extra pic. It is a very remarkable watch.
So the back says 510.501 like the "standard tachy" (shall we say) black PVD version, though the sticker says 510.547. Interesting that, as it points to the fact that these were actually thread-of-the-mill watches later turned to the boxing version. It makes sense that for a watch of such a limited run Heuer did not make any specific back cover.
The conditions of the back as well are really outstanding, the PVD is matte and still grainy.

Cheers,
Fabrizio