For what purposes?
What is required to protect against, on the 5V/TTL side?
What is required to drive, on the 24V side?
What risetime are you expecting?
Is 1MHz the clock frequency, bit rate, maximum pulse repetition frequency...? Is it a continuous signal, or variable, with 1MHz being a typical or guaranteed maximum?
How much delay is tolerable? Phase shift? Skew? Do you need multiple channels with matched delay (e.g., gate driver)?
Tim