I've had great luck using aerosol poly to touch up spots that have been sanded/modified. My trigger finger was encountering some of the fillet behind the trigger guard, so that got the treatment as well.
Finish with fine sandpaper, or even polish it with fine steel wool; then spray it. It's no big trick to blend it, with doing the entire grip.
Altamonts are now OEM on many Smiths.
Moon