RE: Welcome to Club SAITO !
Snap On have a good range of thread guages in both Imperial and Metric, both modern and the "ancient" thread forms. Like the others I wouldn't be without mine or a good set of taps and dies. I think at last count I have about 200 of each ranging from 4BA up to I think 1.5 inch covering every type including those things the frnch used in some of their a/c.
Tread giages are a must have item.