This isn't typical unless you're running some sort of Non-profit or charity organization. 

If the estimated profit is 30k, is that worth the risk?

And all that conjecture can lead to  a major brain hemorrhage.  

If you are doing a flip, make sure your profit margin is high enough to do it right.

I see this being a major issue long term.

@Richard Sherman I received a profit and loss statement from the previous owner’s realtor, copies of lease agreement but no contact details for tenants just the names on the lease.

He's looking to turn it into a 4br 3bath and possibly turn the basement into a livable space.He offers a promissory note for a payout of either a set interest rate or percentage of the profit, whichever is greater.

It shows he believes the property is profitable.

A contractor may do it, but expect to either pay for their time, or have them flat out say no, due to the fact you are wholesaling and won't even be purchasing the house.Also don't forget to account for all holding costs, lending costs,closing costs, etc when you tell your buyers about the "profit".

Hard money is really only best for investments where you have room to cover the expenses and still make a nice profit for yourself.