B29s require more time, and distance, to get where they need to be. Don't take off 1/2 a sector from the fight. Try 2 bases back.
More like 5 bases back, because the B-29 keeps up a much higher speed over ground than the Lancaster while having a slightly higher rate of climb.
Here is a comparison of the climb profiles of the AH heavy bombers with maximum load:

You can see after 40 minutes the 29 has crossed 20k while the Lancaster is still at about 18k, but the B-29 is already one sector ahead. The distance covered during climbout combined with the difficulty of finding a suitable takeoff base is what requires thorough planning from the B-29 pilot.
'd like to do more damage to an enemy city than a set of Lancs can manage and had high hopes for the B29.
If you are really talking about the
City and not just the towns at airbases, the heaviest bomb loadout are not the most effective ones. The best choice to attack the City itself is the 56x250lb loadout as 3 250lbs bombs are just what it takes to destroy one city block. The increased blast range of 1,2 or 4k bombs doesn't help much due to the size of the city blocks. With the 250lb loadout, it's just one drop per square (provided that you fly a formation). A perfect run would take down the City to 34%.
The second best choice is the 80x100lb loadout. At a net bomb weight of only 8,000 lbs you can bring down the city to 53% (.salvo 2 per square). This lesser bomb net weight does even allow you to take even less fuel as your rate of climb improves substantially.
If you chose the 56x250 loadout, you have to expect about 30-40 minutes of loitering over the city target at high altitude, as setting up the next run takes a lot of time and room.
A detailed bombing guide is in the works.