I doubt the Master version works with a B and 2nd processor, or is it a Master and a second processor? I can't really recall what hardware went with what, to be honest.
Buying Elite is really about getting the box and its contents, since the game itself can be found easily enough online (Ian Bell's own site, for starters). Get hold of EliteA and try that. It does the impossible and improves the original game (BBC B version, not the Master). That has a second processor version that I wouldn't mind seeing, which is apparently a bit faster and has a greater variety of ships at any one time. Do any of the BBC emulators emulate a 2nd processor?