Bill: Heres a picture of my Parham stab on the RAF I had. It had 2 degrees leading edge down with reference to the keel.
Worked very nice.......and felt very stable. Pat Mcnears machine is a different animal....2.5 engine that is cranking almost 200 horses. I agree with Ron that the further back the better. If I recall Pats was back another 20 inches.
If you want Pats cell number...PM me and I will pass it along. I dont feel it proper to publically give it out without Pats permission.
Stan