I so need to catch up to you on deadlifts! I just hit 405 on Friday...
Just keep puttin the work in and you'll get there. This is a random correlation it may or may not have actually worked, but as my anaerobic conditioning went up so did my deadlift. Prowlers, grapplers, sled work, and suicides with a weight vest and sled work are all really good for lifting heavy ass weights. I just followed what Wendler did
I heartily accept the motto, "That government is best which governs least"; and I should like to see it acted up to more rapidly and systematically.