I'm not sure you can use alternate valuation date for joint tenancy property that immediately becomes the property of the survivor.  Isn't date of death then the date of distribution? 

"In the case of property distributed, sold, exchanged, or otherwise disposed of, within 6 months after the decedent’s death such property shall be valued as of the date of distribution, sale, exchange, or other disposition."

But why would you want to cheat your client out of higher depreciation deductions for 1/3 of the year?  Just because it's the lazy thing to do?