How to transfer property from relative without capital gains

[Blake Cougle]

My mom is turning 90 this month and is no longer interested in a 7 unit building. I want to take it over but the capital gains would be 50k. Upon her death it passes without CG and transfers with a $0 basis.  I want to upgrade the units (cir 1974) to increase rent and improve the quality of tenants. 

I am considering a master lease and a letter of understanding with my siblings to keep the building at its unremodeled value when it transfers, and will buy them out at that time. I am a 66 yr old retired General Contractor and would like to get the remodeling done while I still can.

Any ideas?