I know it is not recommeded. However, would it be possible to purchase a replacement Phantom 2 Vision+ Camera with gimbal and put it on a Phantom 2 Vision(regular version without gimbal)? Thanks!

It would be cheaper to buy a new Phantom 3 Standard.
Even if the camera and gimbal fits, which I am not sure about, you will still need the Wi-Fi transmitter that sits inside the V+ body (the Vision (egg) has the Wi-Fi unit in the camera housing).