I also have an '87 750, can't tell you about the air box mines been gone for along time for the K&N's. But taking the carbs off is easy and about the only way to clean them good. they are real simple to clean just take your time and be careful with the screws that hold the bowls on, they are soft aluminum and easy to strip, use a good fitting phillips.
Here's a picture of my dinasour.
Here's a picture of my dinasour.
