Pa Conshohocken was a tip o' the hat to a friend of mine, Russ Ceccola. Russ, who's from Conshohocken, was a writer in the games industry (as I was before jumping over to development): a game critic, strategy guide writer, columnist, and general bon vivant. He had actually helped me at one point by settling an argument I was having with Roberta Williams over an interview that Russ had done with her for Computer Gaming World over a game I had co-designed with her, "Scary Tales."
Well, we were talking back when SQ6 was in development, and at one point, Russ said, "Hey, I'm from a city in Pennsylvania called "Conshohocken." I wonder if there's any possible way for you to mention Conshohocken in the game."
Once I decided to make Conshohocken a character by turning the PA into Pa, assigning the name to the liquor store owner was easy, since I didn't have many characters who would be old and crusty enough to be nicknamed "Pa." I also thought it worked out well since making him a liquor store owner would be a sort of elbow-to-the-ribs thing to do to Russ.
So it's a pretty simple answer to a mild question!