'68 Diver needs a prop

[Classic]

Greetings all,
Joel and I replaced the forward sole and casting deck on the '68 Diver ("Real Classic" thread under classified forum).
Pics will come when we figure out how.
We just mounted the 90HP Yamaha but wonder which prop will work best.
Dealer said we were grossly underpowered since everybody is putting 150HP & up on these boats. We are not interested in speed or brackets.  The original boat weighed 1650 lbs. stripped and ran fine with twin 50hp according to that intrigueing article posted by JimCT (We are indebted to you sir).
So we have this 13 & 5/8" X 13" white prop that looks amazingly like a fan blade and is supposed to do 23 knots.
Other option is a 14" X 17" that pushes the 22 ft. mullet skiff fine with only a 75hp 4-stroke Yamaha.
Does anybody run their Flatback with minimal power and have the prop dialed in?
Those Guys

[Classic]

Done deal.
Didn't like the look of the fan blade (13 5/8 X 13) so we went back and got 13 1/2 X 15 to start with.
Worked fantastic.
Got up to the magic 5k rpms and were done.
Tonight we're taking a couple rods and a GPS.
Bob

[JimCt]

Gotta see some pictures!!!  Get some of her in the water showing how the dive platform looks in the down position.  Be interested to hear how you do with it for diving.

My next AS will be that same boat, if I can ever find one.  She's a treasure.