Regarding the fasting time, I think there's a big difference between the IF you are doing and eg the multi-day fasts people here are talking about. They don't sound helpful for strength sports.
I would agree that multi-day fasts would not be good for strength sports. There doesn't seem to be a authoritative source but LeanGains states you won't lose muscle if you're fasting less than 24 hours. (https://leangains.com/top-ten-fasting-myths-debunked-major-u...)
Longer fasts are something different entirely. They have their place, but are more of an event that must be planned. Personally, I like things I can do for life and turn into habits. I don't see how I could make 3-7 day fasts a habit.
Oh, and I'm not the person you asked, but my best DL was conventional 525lb weighing 199 :)