You mean you just want the ships to have the same roll so neither is upside down relative to the other? Makes sense to me that you'd adjust the roll of the targeting ship to match the target's roll and then you'd use:
to get the pitch the ship should be at to be facing the target and slowly adjust it's pitch until DeltaPitch equals zero.
DeltaPitch(ship, target)
to get the pitch the ship should be at to be facing the target and slowly adjust it's pitch until DeltaPitch equals zero.