modernizing a 76 360wr

Does anyone know the sizes of the ball bearings (ball diameters) for upper and lower steering head bearings on 78 and 77 husky AMX?

3mm or 4mm. Measure 1 if you have one. I believe it is 3mm but don't run out and buy some as that may be an error on my part.

3/16ths.

Odd size for a metric bike, I found this out when I rebuilt my 73

Then the correct size would be 4 mm. I know when I measured the set I removed from the only ball and cone Husqvarna frame I ever had they were metric and definitely not SAE. 3/16 may work but I doubt it is correct. Radial difference between 4 mm and 3/16 is .013"

I have little doubt that in Your area there is a " Vintage " class that You can race these bikes in. You might not be in the same race as Your buddys but You will be at the same event and can hang out with them. Here in the Pacific NW only about 1/3rd of the bikes that go to an event fall into true Vintage Classes. So if You start modernizing you bike it will fall into more modern classes.