I think I would remaking them using the unsweetened chocolate to see if they're better. It can make a difference substituting one type of chocolate for another and you have to be careful. Sometimes it works and sometimes it doesn't. (different fat ratios for different types and if you add sugar and/or milk in there... a good book on chocolate would do a much better job explaining than me I think it was one of Alice Medrich's that I read)
And if you don't have unsweetened chocolate, a better substitute, at least for brownies, is cocoa and butter. I use that at least half the time because I'm always forgetting to buy the choc squares.
1 sq unsweetened chocolate = 3 Tbs cocoa + 1 Tbs butter
My brownie recipe, which is the one my mom always made and so dates from about the same time as yours, calls for 2 squares of unsweetened chocolate for a square pan. We use the Baker's choc unsweetened squares.
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