Analyzing whether it's a good rental or not for Duplex - west phi

[Jason Forman]

Hi, so I have this duplex under contract and I know of the 1% rule but that is for single family.  How rules do we follow in philadelphia.  The duplex is in 19143 near cobbs creak park area.  1320 sqft.  Each unit is 1 bed 1 bath with a storage unit on the side with it's own entrance.  

Any suggestions on how to analyze the deal?  Single fams go for 220k in this area but no many duplexes have sold.