Upload some photos to your album page, including details of the lugs:

https://www.bikeforums.net/g/user/513215

Are you sure the frame is steel? Shaped tubes are more common with aluminum frames.

One of the first things to look at is the shape of of the dropouts. Quality bikes will have forged steel with a 3-D look, and an integrated derailleur hanger. Cheap bikes will have a much flatter looking pressed steel and a "claw" derailleur hanger.

The orientation of the rear dropouts and whether the bike has both dowtube and seattube water bottle bosses can help date a frame.