Help! Trying to guess how much to OFFER??

[Steve Candor]

Already has offers. 

Asking $63,000. 1 tenant pays $475. 2nd tenant vacant.

Rents in the area go for about 850. I will have difficulty kicking tenant 1 out. 6 months.

Needs cosmetic work and new roof (water damage). damage could be between $5k-$30k? not sure the extent of the water damage. 

How much do I offer? What would be overpaying? A very similar property sold 6 months ago for $82,000 but included a new roof and gas boiler. $28 a square foot (the place was bigger).  Everything else similar is $80-120k in this area.