In 1st ed. AD&D there's the Reaction/attacking Adjustment awarded for the highest (and lowest) 3 scores. This provides a modifier to missile attack rolls and also adjusts how many segments the character is surprised for.
The cool thing about this is that with this adjustment high dexterity characters could be surprised for zer oor less segments, and therefore not be surprised.
Now, if you don't use surprise segments, but you like the mechanic of high dexterity characters' pantherish reflexes allowing them to avoid surprise, what you can do when the d6 are thrown and the party is surprised is subtract the characters' dexterity bonus from the monster side initiative roll, and if that sum of that operation is equal to or less than the party's surprise roll, then the character isn't surprised.
Or you could just roll a d8 "Surprise Save", that I crunched the numbers for using the AD&D guidelines, and ignoring weird AD&D corner case where a monster isn't surprised because the party is more surprised, and got this:
Dexterity Missile Attack Modifier - d8 save to not be Surprised
+1 - 1/d8
+2 - 3/d8
+3 - 5/d8
You can streamline the process by having the DM or one of the players make the Surprise Save for the high-dex members of the party.