Honestly, it's not that impressive because I weighed 145-150, so in an absolute sense it wasn't that much. Most of the training was with mat pulls (~5" elevation), and with chains. Since the top half the lift is easiest for me, and I was trying to build muscle -- rather than improve my 1RM -- I used the chains to make the tension more "even" through the whole ROM.
With my training setup, it looked like my top set was 405x3. With the chains that made it 405 (2.7x) at the bottom and 440 (2.9x) at the top. My top set of 5 in training was 395/430.
I don't actually know what my max was from the floor. I know around that time I pulled 365x3 easily from the floor with octagonal plates at a commercial gym I had a 1 month membership to. (~2.4x BW)
So, I guess, take from that what you will. I think the relative numbers make it sound more impressive than it is.
Probably the biggest takeaway though is that as long as you work into it, and the training load cycles frequently enough, deadlifting can actually be done fairly frequently. Even if by deadlifting, I mean "mat pulls with chains".
The setup I was using: