All,
Thanks again for your replies and help.  Since my
question piqued some interest, I have attached my
preliminary concept drawings.  My thought is for a
fuselage similar to a sailplane, with 2 tandem seats.
Very narrow and only as long as it needs to be, but
with a more upright seating position.
I might have to sweep the wings for aerodynamic
center of lift / center of gravity purposes / and main
gear balance purposes.  While
not strictly to scale, I have 'shown' a 60-inch dia
prop in the pusher version.

The high-nacelle "tractor" version is not to scale, but
I am concerned about high speed stability with the
prop thrust line up high.  I want 350 knots cruise
AND reasonable stall speed!!

The 'smaller diameter prop' idea was mainly to allow
shorter main gear, and allow the engine nacelles to
be close together, thus keeping the overall size of the
airplane as small as possible, but small props are
not mandatory.  I am trying to minimize the adverse
yaw effects of single engine loss, and use two
affordable 2-rotors in a marketable version.

I have read a little from Jack Norris  and have seen
pictures of the Whirlwind props.

Thank you all for your help and comments.

Gene Kahn