There are myriad scripts for Neverwinter Nights 1. I am sure there must be a way to take a given NPC from the custom list, and place a script in OnSpawn (or somewhere else) to make them spawn with a randomly chosen head from a list of user-specified heads, that way you can make certain...very goofy looking heads from the Community Expansion Packs not show up.

Let's get this out on the Internet in a public forum so people can know how to do this, people.