I'm pretty sure I know the answer already. Singatirin honyaki sujihiki closer to 290 than 270. Marvelous knife in all respects except it wedges a bit with harder foods. With my mediocre sharpening skills I'm hesitant to try thinning a honyaki.
Width of Spine at Handle- 3,6 mm
Width of Spine Above Heel- 3,3mm
Width of Spine at Middle- 1,9mm
Width of Spine 1cm from the tip- 1 mm