As with Dennis, my vari-grind fits a 3/4" without a problem. Maybe Oneway came out with a smaller version recently.
For what it's worth, I used both the 3/4" Glaser and Thompson for years. Now that they are nubs, I plan to keep the handles and replace with 5/8" Dway.
Reason: I'm not a bowl guy and never venture out far enough over the toolrest to justify a 3/4" - I'm guessing that a 5/8" in those massive shot-filled handles will work just fine.
Perhaps guys doing big bowls need the size of a 3/4" that will go 3"++ over a rest - I never go over an inch as I only use bowl gouges to do the outside of hollow-forms.
To make a point, my gouge of choice was a 3/8" for Planet Mesquite - I only used the larger gouges in the "ker-chunkin" stage and the 5/8" was every bit as appropriate as the 3/4".
Actually my larger concern was the log snatching part of my anatomy - to hell with the gouge.