One thing I'd note... as a Moskwa II owner, I can't imagine it without also adding the Ostankino expander... it adds so much functionality and fun. I'd suggest making room for that, if at all possible.
-- Shakespeare

Oddly enough, that came to mind when I was working out my variation, but I noted that the problem with adding that to the Moskwa II was that the Moskwa II was taking up the necessary space for its own "helper" module. Hate it when that happens...