How am I supposed to make an offer?

[Antonio Bodley]

I have a motivated seller that wants to sell his tenant occupied home. I have a bit of a problem. I spoke with the seller and got information about the house that is different from what I found in public records. The seller said the house has three bedrooms two bathrooms and a den, but he does not know the square footage. I checked public records and online sites that says the houspe has two bedrooms, one bathroom, and is 1,008 square feet. How am I supposed to make an offer on a home that has inaccurate information? I cannot run comps on property with inaccurate information, and I will not be able to determine the ARV to make a good offer.