Being a Cub Flyer myself...I'm thinking you need negative incidence, not positive. See Pic of Gold berg Cub....notice the negative incidence ?
It measures 3/8 ". Yes, three eights of an inch.
MUCHO !!! I've been flyin' this Anniversary Cub for about 14 years. That straight edge is aligned with the horiz. stab.
If you have down thrust in the engine...take it out...it is not needed, and is compounding the problem.
Is the plane super nose heavy ?
And tip stalling...

There's something seriously wrong here. Is there a warp, or any wash-out at the tips ?