Terry,
Sure, it's your model.
Seriously though, moving the wing back also affects the tail action. It should probably go to the same distance aft of the wing as on your tailheavy one. Wood is lighter than engine/tank/wheels, so you should still get a better CG position. I presume yours is from plans for the SIG profile bipes?
Should help, unless, that is, you'll use it as a Classic entry. Does it qualify? I forget when SIG brought out the profile bipes... If there's an appearance point judging guideline, you'll take some dings off that score, at least. Some organizers might take objection to a pretty visible mod like stretching the nose (which has the same effect as - and looks a lot like - moving the wing back. Since you're cutting the wood, anyway, stretching the nose pieces is probably easier.).