I have learned to adopt over the years, not least wrenching on Danish trains with American made engines in them, so you learn that 5/8 = 16 mm / 3/4 = 19 mm and so on, but some sizes just don't mix up that good at least not for a fork like wrench then you need something a little oversized but at least gripping on ever corner/side of the nut/bolt.
Old Land Rovers are also imperial as i recall, and not forgetting the US cars my friend tried my hands at.
Actually tomorrow the 2 spare rear axles for the dodge ram-charger are going in the trash, if we are still able to get them onto the trailer as both me and my friend are pretty weak shadows of our former self.
So now he just need to offload the car itself with the rebuild motor being the most valuable thing in that wreck on wheels.