What type of agreement do I need for a Subject To deal?

[Andre Galaviz]

My brother and I have a potential deal in Las Vegas. The owner is a good friend of ours and agreed to do a deal with us if we helped him rehab the property. I have limited knowledge of Sub To deals, despite Pace Morby's excellent efforts to make Sub To well know (Sorry, Pace, it's me, not you!) My question is, what type of agreement do we need to get this deal locked in (I thought my BP Pro membership would have some agreements, or something - not finding anything)? 

We have started down the road of fixing the place up, because we have a strong personal relationship with the seller, but it's time to get this in writing and set this deal up legitimately.

I'm going to jump on YouTube and watch some Pace vids, but any other suggestions, resources, etc. would be greatly appreciated. 

Thanks in advance for any info!