Aware that you want "expert help" but you need to understand that life estates and remainders need to be valued using IRS actuarial tables and if you look at the info at the link it's complicated.
IRS Actuarial tables
No matter what your basis would be whatever your remainder was worth in 2017 and that would be based on the actuarial tables. Something else is a gift tax return should have been filed in 2017 when you got your remainder interest.......there's no annual gift tax exclusion because a remainder is a future interest.
The sales price would also be divided between the life tenant and remaindermen according to the actuarial tables which would be different than the 2017 values.
So this is really something that you need to get a face-to-face meeting with a tax pro for because it's a very involved matter.
