I think you'll find that the clutch pedal won't go down far enough to fully disengage the clutch without the dropped floor.
Like DC says, even if you went for a flat floor and floor mounted pedal box, it'd be quite difficult to make it work - even with the bulkhead moved back in the Miglia the front tyres might still foul the ends of the master cylinders on a typical installation -
http://www.ebay.co.uk/itm/Floor-Moun...item35b52b5a93
You could always give it a go though...