I'd have to find my training logs, but I don't remember ever getting weaker during that time in my life. The guys I was training with did 5/3/1 with FSL and Joker sets. It was simpler than it sounds, but probably more complicated than necessary. I imagine you could probably do Andy Baker's K.I.S.S. program that you can find on Google.
However, if you deadlift 600+ you are already stronger than 99% of all BJJ guys in the world. Period. So if you just maintain your strength you'll still be fine. The fun part is getting submitted by guys that probably can't ever deadlift 315 lbs