5111, first, you have only one week less and unless you have some DNP lying around, I don't think you can drop enough of 280lbs in one week to make a difference. Therefore I suggest you use the rest of your cycle to concentrate on building muscle. The best way to do this is by eating above maintenance, especially on the protein.
When you come off M1T you are going to drop A LOT of water weight in my experience (~10lbs possibly given your size). This is natural. You will also lose some strength & muscle because of the sudden drop of androgens in your system. M1T will have shut down your test production totally after that long. This too, while not good, is natural and to be expected.
Now you want to keep your muscle and strength, and to do this you need to do two things.
1) Get your test production up ASAP w/ proper PCT
2) Continue to eat above maintenance during your PCT period, you do NOT want to go below maintenance because your body will use some of your new hard earned muscle for energy. Not good!
I recommend you follow the above protocol, and do PCT for 4 weeks. You should eat as clean a diet as possible, but w/ the above calorie recommendations. Whenever you finish PCT I suggest you begin cutting by now dipping below maintenance calories. Add some HIIT cardio, try an ECY stack & some lipo-6.
Do this for 2-3 weeks and see how weight loss is going. On the above I would aim for 2lbs a week or so, no more or you will drop muscle.
If you do not like the results consider trying clen, triac, UA, DNP, etc. If you go with one of these I would pair them with an androgen, not M1T but possibly M4OHN or 1-test.
Best of luck! (hope this helps!)