Newbie here, How much would you guys offer

[Ravi Rai]

Hi Guys,
I have been soaking the great information here for the past few days and this my first post here.
I am planning to go and take a look at a two family home that brings in $600 and $580 a month rent and has another $2500 a year in billboard income.
He has listed it for $110,000 and if the house looks OK I am thinking of making an offer. The location of the place is right where i want it to be but my only concerns are that it is a old house with a flat roof and is built in 1890.
If I understand the 2% rule i should I be offering him 80,000? I was thinking of making an offer of around $70,000 but do not want to make a really low ball offer. Any thoughts and input will be really appreciated.