I don't see much benefit in drop sets for compound lifts, but that's up to you. And I was just basing your 1RM on your on 315lb lift. If it's higher, it's higher.
I would take your 1RM, subtract say 30 lbs. Use that weight as your last 4-rep set. Subtract 20 additional lbs for each set prior.
The point is a more gradual jump in weight, as opposed to going from 225/10 to 295/6.