slowrotor,
What about the V-belt (not cog-belt). It does not have the efficiency of gears but it is 'one stop shopping' for; speed reduction, axial, radial & torsional vibration absorption, misalignment, and soft-start.
It appears to work well in the R-22.
The 3VX Gripnotch by Morse and the Poly-V by Browning are two considerations.
Dave