Which is why here in Sweden they still use pre metric measurements equivalent to feet (fot) yards (Aln) and inches (Tum) and the local narrow guage railway 50 aln away from my flat has a gauge of three swedish feet.... oh yes lumber can also be bought in pre metric sizes. Beowulf
Yes, I have one similar to that - however in the specific instance I quoted I didn't take it with me, nor would it have been of much use and more importantly the screws in the hardware shop were in sealed clear plastic containers and the descriptive label quoted only length and "gauge" without stating thread type or whose "gauge" they fitted. The diameter required was dependant on the tubing I could purchase. (i.d. unknown until purchased)
Imperial measure has roots probably back to Pharaohic Egypt as well as Babylon and ancient India. Many of these measures were designed mathematically to have a large number of even dividers. I'm not sure about measures like the cubit, but I'd imagine that in use it was divided and multiplied by values that gave a lot of even divisors also.
Certainly our clock, with its hours, minutes, and seconds, has these properties.
When ancient engineers worked on early gearing, they needed to be able to use evenly divided circles. In fact, they needed to use circles that could be divided using only the classical dividers and straightedge.
This, rather than a barleycorn, someone's foot, or someone's arm, were the justifications for the Imperial measurement systems.
On the other hand, 10 as a basis is obviously anthromorphic - and not very useful; try using a compass and straightedge and dividing a circle into ten equal parts. Now do the same thing for twelve parts.
On topic though, what is needed is digital calipers and digital micrometers that allow more than just selection of metric or imperial. They also need to allow setting of scaling factors. This would allow the readout to be given in any arbitrary scaled units.
More apt to be both useful and achievable would be a set of gauges for thicknesses, widths, and diameters. Along with this would be gauges for screws and bolt heads, although they would be much harder to produce.
By the way, what is the 1:75 scale model a model of? If it is early 20th century motive power or rolling stock, it would most likely be a model of an American made unit. Which means that the original was built in Imperial units. So, all of the metric dimensions you have are a conversion to begin with. It's one thing if the manufacturer gives dimensions in 1:75th scale, but if they list the prototype dimensions in Metric, I'd say they have created a real problem. On the other hand, if they list only scale dimensions, all that is needed is a Metric reading caliper or micrometer.