Good morning Daddyo,
Print off my post and show it to a good prop guy. See if he agrees and see if he can/will interpret the dia that will work and if it's too big for your 2.5-1 gear. What you really need is a 3-1 gear.
FD yup .. very close. So close that in some conversations she could be called FD. But technically not. Some FD Seaton designs have some emersed transom to but it's smaller than yours and the buttock line is much steeper.
You could fair in the trailing edge of that keel by adding on to make a tear drop TE.
North Western Washington State USA