Which screw holes should I use for this old fan-rated box?

Hello,

I’m in the middle of replacing a ceiling fan in my home.

The previous owner used wood screws to mount the old fan bracket directly to the #8-32 flange holes (the outer "ears"). When I googled it, most sources said fan-rated boxes should have #10-24 or #10-32 machine screw holes. I bought both, but confirmed the flange holes on my box are for #8-32 screws.

The box is a Valen Mfg. Co. Model QFH and the label says it is fan-rated for 35 lbs: https://imgur.com/pZNjUdf

It has three additional threaded holes at the very top (back) of the box. I’ve already used one for a ground pigtail, and they appear to be #10-32: https://imgur.com/QYUHvIW

My questions:

Since the box is 1.5" deep, should I mount the bracket to those recessed #10-32 holes at the top using ~3" machine screws?

Or is the flange with #8-32 holes actually sufficient since the box is labeled as fan-rated?

Any advice is appreciated!