OK Bro, here is the deal. You are 6'4 and 200lbs @ 20%... I think you could live with a 20% reduction (I'll get to that). As for the 5x5, it is a great program when you are eating enough carbs to fuel the lifts (it did wonders for my strenght).
So the first and maybe most importnat question is:
What is your main goal? Do you want to look ripped? do you want to increase strenght? do you want to preserve muscle?
Note that Size and strenght are NOT 100% related (this is the number one critique of PowerLifters towards body builders: Their strenght is pathetic compared to their size).
You have to decide what you want to be, a PowerLifter (All in sake of strenght) or a BodyBuilder (all in sake of size and physical appearance).
Don't get me wrong, you will gain strenght as a a result of your size (and this is somewhat valid also the other way around), but the training methods differ ENTIRELY.
So, first thing firsts: Make up your mind about what you want to do, then we can discuss whether it makes sense for you to keep doing 5x5 (nevertheless, it is always a good idea to shock the body every once in a while by doing things differently).
As for your diet, this is my recommendation, with a 20% deficit, Caloric/carb zig-zag
Mon-Tue-Wed-Fri-Sat
2.407 Kcal
45% 271 gr Prot
25% 150 gr Carb
30% 80 gr Fat
Thu-Sun
2.557 Kcal
224 gr Prot 35%
320 gr Carb 50%
43 gr Fat 15%
This diet is not thought for the 5x5, but for a program where you train legs or back on Thursdays/Sundays (to use those extra carbs). With 5x5 you are squatting 3x/week.
Now as for cardio. I'd say:
1. get a Heart rate monitor, I particularly like the Polar A3: cheap and gets the job done.
2. start by building your cardio time up to 45 mins
3. now that you are doing that for 45 mins, keep your heart rate at at 70-75% of your Maximun Heart Rate (the manual of the watch will tell you all about that)
4. You can start with 3 days per week, either mornings or after your lifting. NO CARBS BEFORE CARDIO, after, if you do it after your lifting, have your PWO shake
5. Once you plateau, and you will (we all do), get the secret weapon... ??? add one more day cardio... repeat until you are doing cardio 6x/week at 70-75%
What to do when you plateau? increase intensity of cardio... yep, up it a notch, all the way to 80% and keep at that level
What to do once you plateau at that point? (and you will). easy. Take a break, eat mainteance cals for 2 weeks (even a little higher), go back to a 50%C, 30%P, 20%F ratios and do no cardio ( or once a week for fun). During this period INCREASE all your lifting weights.
By the time you do this last thing, I can guarantee you will have dropped some fat pounds.
I lost, over a 12 months period, 70lbs. Out of those 70lbs, I lost 0 lbs muscle (I actually ended with 0.5 lbs more muscle as originally.).