That circuit should work fine.
As far as sensors, you could definitely set up the sensors as shown in the picture on that page-
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The 20 K var resistor there will let you adjust the sensitivity- read up on comparators if you are interested in how, and you probably should be if you are going to have to explain this project to anyone ;-) It's better to understand how comparators work anyway, you'll use them a lot. For the comp chip, I'd say use the LM339.
For the sensors, you could use the sensors that he used-
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TX would be a infrared LED, and RX would be an IR Transistor.
You could also buy an IR LED and an IR Transistor in a package already... that is easier to interface.