Build what you got and I have learned something from every contest I have been to. I look back at my first attempts building scale moels, but if I hadn't built those first models I wouldn't have learned what I know today. Tim is right, do the best you can and every time you build a new model it gets better every time. I always learn something new from every contest I go to even today. My first attempt had lots of flaws and even today I still don't get everything right.
Don't give up! Build the B-29 to the best of your talents and have some fun. Push the wing forward to match the 3-view and it will be fine. Ed Mason has flown one of the these model with success. I will be flying my B-29 in two weeks at our local contest here in St Louis and really enjoy seeing all four motors turning. When she lifts off it's a sight I enjoy. I built the model first for me to have fun, and then contests were secondary.
Enjoy!
Fred