I haven't looked at the spoiler yet, but here is what I think.

With the preflop limp you allow him to enter with no idea of what he has. On the flop when you lead out and he calls, I would start to get concerned. With the turn pairing the board and being top pair, I would almost consider either check/fold or a check/call. You can assume he doesn't have the K, but you also have to assume he might. You have no knowledge of where he stands based on the preflop action.

I think at least a min raise, if not a 3x the bb raise with your action preflop. If he folds you pickup a smaller pot, but you still have all of your chips. If he calls, you can start to put him on a better range and act accordingly on the flop.