Hi @Eric Huebner Step 1: FIND OUT WHAT THE SELLER WANTS. Sometimes people care deeply about the interest rate; sometimes they want a certain amount of income to supplement their retirement - very possible since he's retirement age. Once you know that, I would approach it this way:
$425,000 Purchase price
-$42,500 You didn't mention a down payment but I'm assuming 10%
$382,500 Amount you're financing
Go here and play with the numbers to see how to get him what he wants. http://www.amortization-calc.com/
At 5.5% and a 30 year term, your monthly PI is $2,172
At 7%, your monthly PI is $2,545
Both are very manageable on gross rents of $625 x 8 = $5000
As far as a balloon, if he doesn't want a big taxable event NOW, he isn't going to want one in a few years either. Listen to people - find out what THEY want and build the deal around that. That's the key.
And further, I'll share something I learned last weekend at Pete Fortunato's seminar in Tampa. If this guy never wants a lump sum, you could refinance this property and take the money and go buy something else - in essence, put the mortgage you owe this gentleman onto another property. See what I mean?