Okay, before I take the next step, I need to be clear on this point-
Are you having actual 68K binary submitted to you for emulation/execution, or are you having human understandable mnemonics (aka assembly language) submitted to you in a text file?
If the former, then you are writing just an emulator. If the latter, you are writing a partial assembler, and then an emulator-- much larger project, but even more fun, and supremely more educational.
Also, how much time do you have?
Let me know answers to both questions... thx.