Dan: What Dave Bacon said. There are lots of present and former Bensen pilots in our community. We can help with the nutsy-boltsy aspects of your project.
The old 1 hp engine-driven Bensen prerotator will be hard to duplicate. A Wunderlich flexible-shaft unit will be more powerful, however, and they are readily available from Calumet Air.
I believe the plans for the all-steel, homebuilt welded Bensen joystick system are available online. Hundreds of them were built and used over the decades. I haven't heard of anyone offering them as finished goods, but perhaps someone does.
Bensen metal rotor blades do not require balancing weights, either chordwise or spanwise. The older wood blades do employ noseweights to achieve chordwise balance. In the Bensen kits, these noseweights were to be made by the builder, using an airfoil-shaped steel strap and poured lead. I'm not aware of any gyro blades that use spanwise weights, though occasionally you'll encounter some that could use some very minor spanwise balancing.
The stock Bensen gyro is rather twitchy and unstable by today's standards. The simplistic tail surfaces design presents the possibility of uncommanded torque roll, PIO and nose-down pitching during low-G events. These characteristics have killed literally scores of untrained gyro pilots over the years, many of whom had time in other types of aircraft.
The Bensen is also extremely closer-coupled in yaw, so that torque management with the pedals is almost helicopter-like at takeoff.
All of these quirks, charms, flaws (or whatever you choose to call them) can be eliminated by various modifications that have evolved over the decades. OTOH, many pilots have learned to compensate for them and fly more or less stock Bensen units. But you must deal one way or another with these oddities or you will be in deadly peril.
Good luck -- from just another old Bensen driver.