I would not use the 74C922, sure it makes the job easy but it's also expensive for what it does. Also there is no need to poll the key matrix constantly. Simply arrange all the rows (or columns) to be connected to outputs say bits 0 to 3 set at 1 and the columns (or rows)connected to inputs say bits 4 to 7. Also arrange for the inputs to be connected to a 4 input and gate with the output connected to an interrupt pin. Then arrange for the port connected to the key matrix to be captured when an interrupt is generated by the action of a key being pressed to de-bounce just add a short delay and re-read the port if the value is the same then accept it otherwise discard and wait for the next interrupt. Simply then translate the unique 8 bit value to whatever you require.