Oil level in forks depending on year?

[1999]

I'm going to have a mechanic do some work on the forks. He asked med to find out the oil level. Haynes says 375 cc and 116 mm for 97 and later US models but my bike is a 1999 Diversion (euro model) with the thicker 41 mm. forks. A guy says he needs 460 ml to reach that 116 but there is no documentation of it . Any ideas?