ADK wrote:
This is probably going to open old wounds. What I would like is experienced
input on the advantages, for economic, efficiency and longevity etc. of
different types of redrives.

I am leaning towards a cog-belt reducer in a 6 cylinder, liquid cooled,
configuration driving a long drive shaft to the prop.

If it means anything, having the redrive and the 4 cyclinder ahead of
the drive shaft probably helps. This means the system would be seeing
a large number of small impulses rather than the small number of large
impulses with a direct drive 4.

On the other hand, the longer that drive shaft is, the lower its
natural frquency, and the larger the gear reduction of your redrive,
the higher the impulse frequency, so those might be coming into range
of each other.