Owner financing

[John McRae]

I am in process of putting together an offer for a multi unit property in the seacoast area of NH.  I currently own 1/2 the building and another party owns the other 1/2 which I am looking to acquire.  I would like to approach the seller with an option for him to owner finance.  He is close to retirement and I suspect he might be interested in a monthly income vs. a traditional sale, where he will likely be taxed on approx $800K gain.  Does anybody have any models/spreadsheets that could help me lay out different options, potential savings to him, etc.  

Thanks