Form for Re-Assignment of Contract + Contingencies?

[Jim Witten]

There's a guy in contract for a property contingent on the permits being approved. So he does not own it yet himself. I am looking to buy this deal off him. I want to go ahead and get a contract in hand to buy the contract off him + X amount of dollars, contingent on permit approval. So this would be a "Contract of Assignment" right? It's sort of a wholesale deal I guess?

However, I need to make it contingent on the permits being approved also.  So where do I find a "Contract of Assignment" that allows for such contingencies? I've Googled around and found this form called Assignment Of Agreement Addendum by California ASSOCIATION OF REALTORS, but it is only 1 page, seems very basic, is that the right form?