Show us what you found. Make us jealous!
Just push the ball out and measure the gap with a ruler, then heat that steel ruler red hot and bend it around the ball to work out circumference, divide all three to get the outcome needed, of course take into account the Pythagorian quotient of heat displacement afterwards and add that to your total....
It's imperial and reading a couple of thou' under 0.625" (5.8"). I suspect the reason it's a little under is because that is by no means a precision ball bearing - it's the most awful thing I've ever seen. Looks like the surface of the moon. You should be ashamed of yourself Bryansfan - hope your other one is in better nick