Hi John,
You are pre-empting my thoughts on this? hahaha.
It's a possibility. I really like the dramatic composition of this specific painting. I think I understand why the watercolour was in black and white, presumably as the storming was done during darkness. But I prefer colour and if I were to make this as a diorama, I would probably do this in colour.
A couple of Sharpe's tv episodes had a forlorn hope storming castles incl Badajoz carrying climbing ladders. I would probably use Airfix Collector's figures for this piece as I have a stash of them... Mind you, this is just a possibility.
Rgds Victor