There are many ways to think about it.
1.) Is the equpment (you included) up to the task? Have you practiced and felt comfortable at that range? (No difference than max range with a straight wall or other rifle cartridge)
2.) Ethics behind taking that shot at a "buck" vs the same shot at a doe....would you or wouldn't you? Why one and not the other?
3.) Situation set up....is it a clear shot or just throwing lead/steel/bolt and praying? Do you have a good rest and is there wind, how much movement is the animal doing?
4.) What happens if it doesn't come together?
90 yards with a 500fps crossbow is about 0.6 seconds of flight time. This is comparable to a 522 yard shot with a rifle shooting 2900fps. There are plenty of examples of that type of shot with modern high power rifles and smokeless muzzleloaders at game (whitetails included since they are more "twitchy") at that range or further on the interwebs.
Can it be done..hell yes, should it be done? that's up to you to decide what your limits, capabilities and ethics allow.