Your biggest concern is suspended losses carried forward. If Turbotax did your return every year you received a K-1 then Turbotax should have a carryforward which it will apply. If Turbotax did not do it every year you need to get each return and K-1 and calculate the Carryforward (suspended loss) which will be subtracted from income from the partnership in the year of sale.
On a practical basis if your distributions are less than a couple of a thousand dollars per year precise allocation amounts are not material - Just get the totals correct. If your distributions are over $10,000 per year your real problem could be that state tax returns could be required.
