Many replacement grips are metal, and the throttle cable hole is part of the casting. You want this kind or a metal replacement throttle tube.
The cheap chintzy white plastic throttle tubes are used because they cost the OEMs pennies. I've had my 2003 Savage since mid-April, have already replaced the tube once (with a Harley Davidson sourced part) and it needs to be replaced again. ALL the OEMs that use white plastic throttle tubes get them from the same source (Taiwan). They are junk, but if you want to reuse yours, sand off the ribbing.
With the arthritis in my hands (fingers are starting to seriously curve), I find ISO and other fat grips horribly uncomfortable. The swell built into Gran Turismo or similar 1960s/70s touring grips lets my hands relax naturally. You can get new GT grips for our bikes from Ryca, run you $12 or so plus any "shipping and fondling" fees.
My stock grips got swapped out for Italian sport touring grips in the first week or two of ownership, and those fancy grips have already been destroyed by the climate here in SW Tennessee. Chunks missing from the too soft, not UV stable rubber...
Go to a bike shop that carries aftermarket grips. Try your hand on several styles and decide what is actually comfortable for you. Grips are like seats, what I like may be agony for you, and vice versa.