Yes, a full is a B and therefore allowed. It would have to be used as a third pass. One pass must be a layout, code specifically says full will not fulfill that requirement and then one pass must be a two element front pass. There are no up to level or compositional deductions or requirements for level 7 so unless it is really high and has very clear form it may cause more deduction than it is worth. That of course is between coach and gymnast.