What it really comes down to is trial and error.
I didn't have much experience either when I started modifying parts to fit my CZ 858. The first grip I fitted to CZ I started out by just trying to see if the mount it as is. When that didn't work, I would inspect the grip to see what exactly was preventing it from fitting. Here's a small list of problems you may encounter and possible solutions:
- Grip screw does not reach the nut/not long enough -> Drill the the base of the grip (if possible) so that the head of the screw and washer sit further down, or purchase a longer screw.
- Angle of the hole for the grip screw does not line up with the nut in the receiver -> With a drill and a dremel bore out the hole to make it a little wider at the top so that you can move the screw around to line it up with the nut.
Note: some polymer/plastic grips may be hollow which would make this a lot easier to do I figure. My experience modifying grips is limited to wood.
- Top of the grip does not fit into ferrule -> Sand down the grip to fit it to the ferrule or with a dremel tool remove the ferrule.
All in all you just have to take your time and be analytical about what you are doing. Every grip is different, there is no set procedure for fitting AK grips to a VZ.