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thank you for these addtional images

we have not seen the frame's distinctive brake bridge previously

this may be a clue which can advance an identification

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alignment -

when you get 'round to the cold setting you will find that the drive side will move laterally slightly more easily than the non-drive side due to the double dimpling of the drive side chainstay

the steel has a measure of springyness and it is necessary to take things very slightly past where you want them to end up with each cold setting as the metal wants to return in the direction it came from

make cold setting adjustments to the rear triangle until the two sides are equidistant from the centreline and the dropouts are 120mm apart

the easiest way to work is to clamp the frame's bottom bracket shell in a beefy bench vise leaving both of one's hands free for the adjustments

if wished, you can do a corrobative test by laying a strightedge across the shell faces and extending it back to the dropouts

the straightedge needs to be at least a half metre in length
test more accurate/reliable if you are able to face the shell first

https://www.sheldonbrown.com/steel-frame-repair.html

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