Dieting in middle of a Bulk Cycle of Fina?

Well I am two weeks into a fina cycle, gained 10lbs so far, but unfortunately my diet hasn’t been too clean, so some of that 10lbs is more fat than I would like. Could I get an intelligent opinion on whether it would be stupid or not to take a week of dieting at say 1500cals w/200g protein, 2 weeks into the cycle, followed by the last 3 bulking again? I reckon I could probably lose 4lbs in that week, which would be great, but would I lose the muscle gains from the past 2 weeks? Or would the fina allow me to maintain what I have gained in that time? Would this hinder the gains in the 3 weeks of bulking following? Or would the slightly lower metabolism cause me to rebound all that lost fat? Any opinions appreciated, cheers.