Overcalling a suit after a 1NT opening bid

So far as strength goes, I agree that overcalls of a weak no-trump should be constructive. The upper limit will be about 14 HCP because with more you would double first and see your long suit later if appropriate. Regarding the shape, I agree you do not want to overcall with a 5332 shape. sometimes you have a 5-card suit and a 4-card suit or even two 5-card suits, in which case you do not want to have always to pass. You cannot make a takeout double of 1NT because double would be for penalties. Sometimes if you are short in one major and have four cards in the major, you could pass first time with the intention of doubling if responder transfers into your short suit.