Operand Type Clash

The error is correct, you can't implicitly (or explicitly) cast a VARCHAR(MAX) to sql_variant. If Name is a VARCHAR(MAX) you will need to convert it to a compatible type (like VARCHAR(8000) in order to pass it in as a parameter to sys.fn_sqlvarbasetostr()

see msdn:

sql_variant objects can hold data of any SQL Server data type except text, ntext, image, varchar(max), nvarchar(max), varbinary(max), xml, timestamp, and Microsoft .NET Framework common language runtime (CLR) user-defined types. An instance of sql_variant data also cannot have sql_variant as its underlying base data type.

If you need the functionality of sys.fn_sqlvarbasetostr() and can't down convert your col without losing data, you may need to roll your own version of that function. CLR would be a good bet.