prestonmiller91, If you port out your Sprint phone number to Google this will cancel your Sprint subscription for that number and there may be associated termination and cancellation fees as well as porting charges from Google.
For more information on the Sprint and Google Voice service please visit @ http://sprint.co/1Ov1ejx
I actually used the same number for sprint and google in the past however it gets to be a pain... using google apps you cannot send text messages and picture messages easily. i'd recommend getting a different google voice number than your sprint number. if you still want your google number you can go to your google account online and go to settings then voice and merge your sprint and google voice numbers. you will need to re-set up your voicemail as well.
Google and Sprint has an agreement for Sprint users to just make their cell phone number their Google Voice number.
I found out today that there are issues with WiFi calling and Voicemail when trying to port the Sprint number to the Google Voice (GV) account. I had to call Sprint to disable the Voicemail, then go to the Google Voice site to enable call forwarding/associate the Sprint number to GV before being able to receive voice messages via GV.