PS
The turbo vs non turbo fuel burn difference is not really very much if you, could or do, run the two engines at the same manifold pressure at altitude. BTW, the turbo gives you lots more knots if you can run at altitude, not to mention the ability to get up there.
As an example from my P337 Owner's Manual: at 6000 ft a 73 P337 at 25" and 2450 rpm is at 54% power and results in 181 mph. At 12,000 ft it is still 54% power 194 mph. IN both cases the fuel burn is slightly over 15 gal/hr. So you get 13 mph at the same fuel burn. Throw in that in my region it is usually smoother air up there, the T or P were my logical solution.
I just finished an exhaustive search of just about every T or P 337 out there and if you would like to converse with me directly about the market I can give you my impressions and some other leads. I am
dave@aldora.com
Dave Dillehay