Start with a true ARV, minus realtor fees, minus two sets of closing costs (for buy and sell sides), minus rehab costs, minus holding costs, minus fudge factor for unknown repairs, minus profit.

Only you can decide if you will be happy with the rerurn on your money, if it fits what you are looking for and the numbers pan out then only fear of the unknown is whats holding you back.

15% profit with all of the unknowns and risks is not excessive. 

Not saying that is the case, too many unknowns, but especially if it was improperly wired, it might have been drawing more than it should and maxing the 60A breaker and taking the house circuit to the max.

A partner and I will be borrowing money for a unknown rehab project.

I am very interested in lease option deals, wholesaling, fix and flip, rental property in the next few years with tenant buyers in them..My first main question is already posted on here, involving a private loan for a partner and I to rehab a house then list and sell.A partner and I will be borrowing money for a unknown rehab project.

The unknown is always the biggest fear.  

My experience tells me that your tolerance for the unknown will indicate if you hire legal help.

Sometimes several dwellings have one meter.This is why I suggested the owner, if he wants to do the right thing, should get all his own facts.........On it's face, the way described, if the contractor did use the neighbor independent water - that neighbor should not pay for the extra costs.A fact finding mission, including where lines are and what meters gauge what is the crux of the case and could produce unknown facts. 

Market shift happens or all the sudden has a larger pool of homes for sale (-2-5%) ... then has longer days on market (another -2-5%) and then they nit pick you because you have been on there and they know you don't have another buyer ... and there goes $3k for closing costs or something.It's just not worth the risk/holding/taxes/larger project=larger unknowns ...