Anyway, if you are actually going to eat sub maintenance calories, I would only do 5-3-1 for the 2 main exercises, and don’t do any plus reps or assistance exercises. I don’t believe that anyone should do sets of more than 5 or 6 on a sub maintenance diet because the main effect of those sets is to deplete a muscle so that it will rebuild, and its not going to happen on submaintenance calories. The only thing that higher rep (6+) sets will do is insure that you lose the most muscle possible while you are reducing your bodyweight.
The more work you do with submaintenence calories, the more muscle you will lose. I would NOT have a slight reduction below maintenance level calories ever. By maintenence I mean what you need to maintain your ideal bodyweight, and fuel your training and recovery. I would either cut fast from 20 to 15% while doing maintenence strength training ONLY, or eat a high performance diet to add muscle and let your body naturally move from 20 to 15% as it wants to do over time.
If you do the fast cur first and maintain 95% of your strength you will get stronger fast when you bring your calories up. High performance OR fast cut and strength maintence are the only paths that work. The in between path is much less efficient and changing body comp and increasing muscle.