If they had proceeded with the DB type engine in the design of the J2M then it would
not of had the fat-Zero look to the airframe. There would have been no reason for
the round fuselage cross-section, it would have had a rectangular/oval cross-section
conforming closely to the engine dimensions, pretty much just like almost every other
V engined aircraft of the period.
So trying to stick a DB style nose onto a Raiden fuselage makes zero sense.