Multiple rental properties acquired via estate distribution. how do i VALUE the asset if there is no PURCHASE cost? in TT Business - S-Corp

Typically, the basis of the property "acquired" by the estate would be the fair market value on the date of death of the decedent. You can check with the fiduciary with respect to that valuation.

Did the decedent actually name the S corporation as a beneficiary in a testamentary document?

The properties were left to the 2 children who inturn created the LCC,S-Corp and transfered property deeds into. So, then, i would guess value at dated warrantee deed to S-Corp? [Probate/deed transfertook 13 months after death]

No, the date of the transfer is not relevant (the length of probate does not matter).

The basis is the fair market value on the date of death of the decedent.