I'm about to sand 2 bedrooms that have been carpeted for at least the past 30 years.
The flooring is oak and appears to be in very good shape. There is a finish on the floor. The house was built in 1950.

My plan is to rent one of those random orbit sanders with the 4 pads.

I did this a few years ago to my living/dining rooms (same flooring) and I started with 36 grit, then went to 80 grit and finished with 120 grit.

Still the same deal?

My plan is to use Basic Emulsion / Streetshoe for the finish.

Thanks in advance

Should work, you will need to scrape the corners.