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Prop size

I chose the 72?

Flying my phase I now behind the recommended 72? prop and loving the performance.
 
My 2 cents

Just my 2 cents, but as always think about your mission. If you compare the same brand and type of prop in a 72" version vs 74" with the same Max RPM on the same plane then aerodynamically the 72" prop should have a higher top speed vs the 74" prop which should have a shorter takeoff distance and faster acceleration. Their is a lot more to it than just that, but that breaks it down to the basic question of which one better suits your mission.
 
There are 76" dia props running without issue on -7s, -7As, & at least one -8 powered by rotary engines. Surely the dia won't be an issue on a -14.

As to speed, the larger dia will definitely improve takeoff performance. And IIRC, when you run the numbers on rpm/dia/airspeed, you have to get a fair amount faster than 200 mph before getting hurt by a 76" prop at Lyc rpms. If it's c/s & you're running down at 2400-2500, like most seem to do these days, the larger dia should have unmeasurable negative effect at speed. For perspective, a Cessna T-210 cruises at roughly RV-speed (faster at O2 altitudes), and runs an 80"+ diameter prop at 2600 rpm.
 
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