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WI freewheels run quite wide from the base of the thread, have you measured that chainline?
47.5mm is easy to achieve with MTB chainsets, but 44T is a pretty big ring for SSCX considering most would aim to use no larger than 2:1.
34:18 drops you down to the cheaper WI freewheels and lets you use 4-arm 104mm mtb chainrings. 47.5mm is a normal mtb chainline and Goldtec make 1/8th SS 'rings, £18ish.
The rest is a matter of taste.
Your criteria are underdefined.