Entering rental sale adjusted basis

I sold a rental that I lived in and then converted to a rental….so the cost basis is on my original purchase amount and not the fmv I entered at conversion which TurboTax depreciates off…I had a gain on the sale and have read posts about this….if I sell by checkin”sold this year” it using the fmv for cost basis instead of my purchase price back when I got it plus improvement etc…..so I am doing special handling and reporting the sale under the “sale of business property” option like has been suggested…..it seemed like the only way for it to work like this is to edit the rental property info and not have “sold” selected…..any thoughts on that ?  It seems to work math wise that way and the capital gain and such seems correct, if I select “sold” under property info it radically under reports my capital gain….but I don’t know what happens next year and such