Deed of variation and SDLT?

I have a client that has inherited a property at £250k and cash of £50k. She wishes to give the entire value away through a variation to reduce her estate for IHT. The administration has been completed and the property transferred to her. She wishes to keep the property and would make a cash payment of £300k.

For IHT purposes, this is still removing £300k from her estate provided done within 2 years from the date of death. However my niggling concern relates to SDLT. The client has inherited the property (no SDLT) but is then intending to make a further payment of the value of £250k effectively from her own funds and not the inherited property itself.

Do forum members have any views no whether this is possible?