How to update apple iPad 2 iOS 7.3.0?
How to update apple iPad 2 iOS 7.0
iPad 2, iOS 7.1, How to update apple iPad 2
7.3 is a beta for developers only.
Pay the $99 fee to join the developers program.
Download the beta and install it.
Any issues you will definitely encounter you will have to fix on your own as you will agree to a non disclosure agreement and will not be allowed to talk about or ask questions anywhere but the developer's forum.