I took some measurements and I have 2-1/2" from the rear of the burner ring to the divider panel and 6-1/2" from the front of the burner ring to the front panel. My divider panel is 11" from then rear. I looked at this video https://www.youtube.com/watch?v=XnkT9ZtE8KQ
and it appears the burner is closer to the divider panel then the front panel.
However I did notice is this video https://www.youtube.com/watch?v=k9t0XBEdVuU
that the to of the burner appears to be about level with the inside edge of the angle iron where mine is sitting roughly 2-3/4" below the inside edge of the of the angle.
Can someone tell me where the top of the burner should be? The panel that is on my burner is the one that came with the unit so I assumed it was correct but it may have been replaced.
The first video is a 350, not a 520. The 350 has a smaller diameter ash ring. 13.5" I think. The boiler and base are also smaller, so not a good comparison. That being said, the back of the ash ring looks to be very close to the divider plate!
The second video is a 520. Like PACOWY said, you need the pot to be closer to the front so the flame and hot gasses can sweep the top of the boiler front to back. If the pot is back to far, the top front of the boiler will have a cold spot. I don't think the height is as critical as the front to back measurement, but, higher is probably better. I should think you don't need to attach the blower housing to the angle iron.