This is a SPAD, a Simple Plastic Airplane Design, not a WWI biplane fighter, Walt.

Folding coroplast, it's very easy to build a warped wing or fuselage, especially if you don't have much experience and are working alone. That's where I suspect the odd tendencies are coming from, not the wing location or the thrust angle. 2 degrees down and 2 degrees right should be more than adequate. I know some of my creations have had up and left in them, and they've all performed just fine.

On SPADs, the wing is designed to be slid back and forth to achieve balance. 2.5" back is hardly extreme, though I'm wondering what point of reference you're using, since most SPADs don't specify the location of the wing. It's normally "just put it wherever it balances."

One thing about SPADs is that there are no rules. You may consider choosing to lighten the tail and/or making the nose longer to achieve the proper balance point.

Frankly, I would just attempt to trim the odd tendencies out. Don't forget that the ailerons should be parallel to the fuselage.