Congrats on the personal record!!
I see some flaws.
For one, you need to sit back further. Second, keep the back flattened at 45 degrees. it appears that you are rounding.
At last, you could certainly use some upper back strength. Start adding some supported t-bar rows and barbell shrugs to your routine. Partial deadlifts would help.
Once you get the form down and strengthen the weaker areas, you should be in good shape to pull 500lbs.
Good luck!!