Welcome to the club
AC/DC is a pretty solid pin, no real issues with it. Some of the early premiums had a 'cloudy' window to the lower playfield which was then rectified in later editions. Other than that I can't think of anything special to look for.
If you buy a HUO or used one, it would be good if it had shooter lane and kick-out hole protectors as those areas of the playfield can be prone to ball damage. I'd also look for a one with color DMD, shaker, lit flashes and cannon mods since those add to the game tremendously (IMHO)
Good luck buying your first pin, AC/DC is a great choice and pinside will have your back if you need any help with it