So pleased I asked the question Simon! I had no idea there are 2 sizes. The Gotoh bridge I have has 74mm centres and the hole diameter is the same. But the post inserts are the small ones like what came in this kit.
I did see online the metric inserts have a diameter of 11.3mm.
I’ll definitely get a cheap set of verniers tomorrow. See a metric digital read out set here for $20.