Too little information provided for a more detailed answer, but that is the general idea.

Quick details:- Seller’s owns it solely by herself in a trust since (husband passed 6 years ago).

First, you need to understand your state licensing laws....many prohibit this, once you advertise the house details, regardless of any “selling a contract” language. 

DM for details.  

Here are some details to have available when making a request with a HML.Must Haves Property TypePurchase PriceARVCost of RepairsHow much cash you have on hand to use in the dealYour credit scoreHow many flips you have done within the last yearCity and State of propertyDo you have a contract?

Are their listings detailed with good quality photos?

I'm sure the GC would like to make at least 10 to 20% of the project costs which would tack on an extra $10k to $15k.With all of those assumptions, you can see why I don't think $70k is an unreasonable estimate for the project.As JScott recommends in his book, when estimating costs for projects you need to put together a detailed list of every repair and then price out each repair. 

@Greg Murphy, can you post the details?

A typical scenario may go like this: I come across one for sale and the owner states the income and something like "good cash flow" in the details.

I'd love to dive into some detail if you don't mind specifically around your underwriting process.