you can try 3 1/4 and see what happens but of the nose is sitting down at rest you will still have the same problem of applying enough up elevator to get the nose to rotate to a take off position.dubru used to make a long nose gear strut that allowwed you to lengthen the nose gear in situations like this.see if you can fit this in place of what you have.
http://www2.towerhobbies.com/cgi-bin...&I=LXD844&P=SM