Lease Contingency Clause / Sales Agreement

[Chris Cosmas]

I want to purchase a new 6 bedroom duplex in Phila . Two uniits with 3 bedrooms and 3 baths per unit.

The pro forma for the property projects top dollar in the zip code. If rentals hit the $4300 projected for

both units , the property will cap rate at 6.5%. Expected returns,6.5% , for new construction returns in 

phila.  I want to include a " lease contingency clause " in the agreement to give me time to obtain

two leases to hit the combined rentals of $4300/ month.  I need ,sensible and fair ideas for seller and buyer,  how to present the terms of 

the contingency clause in the sales agreement.