Penn 750 /850ss handle question

[Poison Frog]

Hello
I have been using old Penn conventional reels for a while. I recently picked up 2 Penn spinning reels that I want to modify.

I want to replace the stock knobs on a 750 ss and 850 ss reels.  I have the handles mounted on the right side of the reels and can't find an aftermarket replacement for the right side.
 
I don't want to have to enlarge the hole for the new knob pin.

Can anyone tell me the diameter of the rivet or the stock size hole?

I want to obtain the appropriate knobs before I cut the stock ones off.

Thanks for your help!

[alantani]

i just realized that this never got answered.  if you are talking about replacing just the grip and leaving the arm, then you will have to drill.  grips made in the US are going to be 3/8ths of an inch.  grips from overseas will be 10mm.  yeah, you are going to have to drill.