54? I've never seen a 54 SunTour ring.
This looks very nice. I do have a question. As I recall the SR500 frame ( the Criterium Frame) had very long dropouts for the wheel axil. The frame as pictured looks more similar to me to an SR400 frame (team comp). I am obviously not an expert but my riding buddy of many years ago was on an SR500 with 105 and the only the that stood out the most from his bike and mine were the shape of the rear dropouts