The MB3 was powered by an early Napier Sabre engine and I've always thought the Griffon in the MB5 looked sort of 'lost', if you know what I mean. My plan for my four Falcon MB5's is to build one with a Sabre (not any Sabre though, a Sabre 7 or 8 which were 3000 hp motors), one will have a turbo-charged Centaurus with an exhaust system similar to a P-47 so I can explain away the use of the radiator duct in another way, and the other two as a JMN bait, done like an F-82. I haven't decided what engines it will have yet.
I've already built a 1/72 model of the MB5 prototype quite a few years ago, it's an Airframe vacuform kit with lots of Aeroclub accessories.