I see those all the time for real-estate deals:  The payments are based on 15-year amortization, but there is a balloon payment requiring the balance to be paid sooner.  Only difference here is that there are three balloons.  But since when can intangibles, inventory, assorted personal property, whatever else is involved with this business (we don't know, do we?) be reported as an instalment sale?  I see it as all taxable in the first year, unless shown otherwise.  

To determine whether any of the gain on the sale of the business can be reported on the installment method, you must allocate the total selling price and the payments received in the year of sale between each of the following classes of assets.