Once you have inspected the property, and discovered no major issues, then you are in a position to make an offer. 

Most institutional investors underwrite $250-300 for CapEx reserve from what I have seen.

I don't think there was intent on your agent's part of not discovering the true age of the building, although a good agent would know the rough ages of the buildings in that area of town. 1959 to 1979 is not just a few years apart and more than likely, unless completely demo'd and remodeled would not be in the same neighborhood, i.e your agent should have known 1979 did not add up.

I recently discovered BiggerPockets while listening to the Audiobook on Rental Property Investing.

Grew up with little to know financial education and discovered the education I needed only later in life.

I have serious doubts if its been converted into a multifamily...I recently saw 150-yr. old tavern that was attached to the largest grist mill in the country get denied registration...Anyway, location is key...if you are in city limits, or have neighborhood (or deed) restrictions you may be facing a challenge...I know a guy that renovated 20-properties and discovered that the siding had to be replicated to the original...he had to pay a machine shop to create a cutter head so he could mill the siding to the original spec for any repairs.

I got one quote from a non-institutional lender and he said 8% for a 30 year fixed..... 

This is how the institutional investors and REITS play the game.They only other way to scale and create significant cash flows from day one with smaller properties is to buy cheap and owner finance and or rent to own on the back end or lease option and rent own on exit.

Somewhere between 2 and 14, you will discover that this is just an imaginary problem that people invent in their mind as an excuse not to take action NOW.

So I was about to close and the buyer backed out last minute as there were roots discovered in the sewer line which I understand is a common problem.