Next time you build one (you know you have to have a Washington!) Google "Terry Dean nose weights". He makes a pair for the B-29 molded to fit between the wheel well walls and the fuselage under the cockpit floor. They're about 3" long (a little longer than the well itself and the weight is just enough to keep it on it's gear without adding more than necessary. (I'm pretty sure the model balances at the CG of the actual aircraft.) They're about $6 plus S&H. He also makes them for many other kits, but I only buy them for bombers with glass noses as I can usually figure it out myself. (You gotta cheat once in a while though, I have a set coming for my B-24D)