I think some of the IIs were assembled overseas but having owned both UK and Chinese built ABMs I don’t think there’s enough of a difference to worry. The big difference is from the III to the IV, the power amp has been redesigned as has the valve drive section, not to mention the 9 rather than 7 band EQ. I own a gorgeous EVO from 1999 which I adore, but the drive you can get from a IV is totally different. The valve drive in the earlier Evos just gives an extra girth - like the old 90s Trace Elliot pres, whereas I feel the VI gives you some more grit and phatness.
If you can stretch to an EVO IV I say do it