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!