425ish seems reasonable.
You're can probably hit peak sets and progress for awhile. Like your peak 4, then next week try more weight for a peak 4. If that stalls mix it up and go for peak 3's or 5's or even 8's or 2's. Eventually you'll need more volume. Like hit your peak 4, reduce weight by say 10-15% and do a couple back off sets. Further down the road it gets more complicated. Deadlift is tricky with volume and progression as you get more advanced.
As far as going for actual 1RM PRs it's usually once or twice a year for me. I hit 700x1 in late 2019, hit 675x1 in late 2018 and 650x1 in mid 2018, no deadlift PRs at all in 2017. Due to injury setbacks I don't expect to hit any PRs this year either unfortunately.
For starting out rep PRs weekly as long as you can should be the goal. Maybe try for an actual 1RM about every three months. Maxing is mostly a waste of a training session you could be improving. Rep PRs in the 2-5 range are a solid way to gauge progress. Even the same weight and reps at a lower RPE is still progress.