Also, do you think the delay will be consistent on each iteration? Even if it's 5 microseconds, I can deal with it if it's always the same.
Well the arduino timer 0 is used in most sketches to support millis() and other timing functions and it uses interrupts so there is always the chance at any given instance where your user interrupt activates but if the timer ISR is active the user interrupt has to wait for the timer interrupt ISR to finish, so there is always going to be some small possible variation in latency timing. It is possible for you to disable timer 0 interrupts in your start-up code but that will eliminate being able to use some of the standard arduino supplied functions.
Lefty