But to be clear, reel 1 - position 7 could be a lemon, reel 2 - position 14 could be a lemon, reel 3 position 21 could be a lemon.
What, exactly, is at each position is not that important. What is important is that each position in the array corresponds to a win or loss. Rather than booleans, perhaps a byte array, with values between 0 and 255. Look up a value for each reel/position. Add the values. Certain totals mean win, while others mean loss. The actual payout could be determined from the totals.
Is an array definitely the way to go?
I think so.