I've seen these frames before:
An entry level racer-style bike, squashed gaspipe tubing, nothing "nice" about it but period and functionality as transport.
A little prone to cracking.
I wonder if it is MBK or similar mass-market euro-brand.
You might find info thru the frame number, and there might be details stamped on the fork steerer, along with residue of the original paint.
A photo of the dropouts,bb and brake bridge helps identify build quality and origin.
I would guess on
plain, thin stamped dropout,
plate brake bridge or Chainstay bridge,
and unthreaded guard/rack eyes.
French bb, he threads? 50:50
Fun project

,
but lucky seller
