Sorry. Changing to a narrower BB (axle length) will likely give you an easier time getting the chainline right.
Your Raleigh's BB is probably 115 to 120 mm as it had a double chain ring. Fitting a single speed freewheel in place of a cassette freewheel can necessitate re-dishing the wheel to move the hub relative to the rim.
Sorry. Changing to a narrower BB (axle length) will likely give you an easier time getting the chainline right.
Your Raleigh's BB is probably 115 to 120 mm as it had a double chain ring. Fitting a single speed freewheel in place of a cassette freewheel can necessitate re-dishing the wheel to move the hub relative to the rim.