A transfer on death account does not go through the Estate. It is now yours (or whoever is named). You have a stepped up basis, as pointed out.
There is no reason to sell any stock unless you think the market will go down now, after eight up years.
The executor is responsible for any Estate, or Inheritance tax and will have to claw back money from you if the there is any tax due and there does not remain enough in the estate to pay it.
