Core as an I2C slave?

[fluke]

I'm going to actually finish building my MIDIbox FM this year.  I'm building it without a control surface, so i designed a stripboard layout for the Core, with banksticks and a 12pin connector to the OPL3 board.

Then i had what i think is a really good idea.  What if i move the OPL3 connection to other pins so that the hardware I2C interface on the PIC is freed up.  Then i could connect the MIDIbox FM Core as an I2C slave to another Core that is being a MIDI Router without needing a PIC16F88 between them.  And i could put my DB50XG in the same box for the complete 90s synth experience. :)

Does this sound like a workable idea?  I know i'd have to extend MIOS to support this, would it be a lot of work?