When I need to do a reversal in my B-25H, and I don't have enough E (energy) for an Immelman, I go up about half-way, then use full rudder, full opposite aileron and pull all the way back on the stick. That gets me doing something like a hammerhead (I think).
I'm still working on when to use the flaps (in any plane).
<S>
Yossarian
EDIT: I do the above manoeuvre when my plane is completely stalled, or just won't really go up much further.