After a little search I came up with this.....
<font color="blue">Nine fin valve covers are correct for all 1956 225 H.P. and 270 H.P. engines. They are also correct for 1957 cars through serial number E57S4500. (A mix of seven and nine fin low script valve covers was used between E57S2000 and E57S4500.)</font>
One of the Corvette vendors has a pair listed for $475.00. As you know prices vary. Sorta like a BE rear end is worth more here than anywhere else.
