i'm told that the above transistors have very similar characteristics but that the 2N5089 has less noise and it is a good idea to use this in circuits with a 2N5088 to give less noise. Is this true? And if I did change them what modifications would I have to make to the circuit?
What circuit are you building? If you change 5088 with 5089 there should be no problem. It's true that 5089 is less noisy. Moreover, 5089 has more gain. They both have the same pinout.