[C320-list] folding props again

[Scott Thompson]

Sorry to beat a dead horse, but I can't seem to find the answers in the 
older threads on this.  Surprise is 1999 wing keel model, hull 653.  She 
has the Yanmar 3GM30F, continuous HP rating 24.1HP at 3400 RPM.  Her 
gearbox has 2.21:1 reduction in forward gear.

For cost reasons and to get minimal drag I'm only looking at the Gori 
and Martec 2 blade folders.  What pitch and diameter of these props 
would be recommended for my boat?  Am I correct that the shaft is 1 
inch, standard US taper?

Who has the best deals on these props?  Any reason to prefer Gori to 
Martec or vice versa?  I've read good things about both.