Irrevocable trust and house basis question

I could use some advice please;

House purchased in 1989.  House was put into IRREVOCABLE living trust in 2007, but no appraisal done.  House was sold in early 2019.   No distribution made to beneficiaries (children of owner) as owner was still alive until end of 2019.  I have received interest income 1099-Int.  I must file a return for the trust for the first time, so I need to calculate gain on sale of the house.  I have receipts for improvements since 2007, but don't have an appraised value of the house at the time it was put into trust.  Is there a means to estimate it without running afoul?    Also, once these gains have been taxed and we divide the trust up among beneficiaries (only the house sale proceeds are in it), do the beneficiaries have a tax liability for this inheritance since it is from a trust not an individual?  This tax stuff is enough to make a sane person crazy...   Thank you!!