cliff6361;
ASME SA 533 is a specification for quenched and tempered alloy steel pressure vessel plate. The grade B contains 0.5% Mo and 0.5% Ni. You did not mention the type of class for this material - 1,2 or 3.
Why are you even considering using a cast version of this material? What is the application? If you need a cast material specification for pressure retaining capability and could be used for elevated temperature service, I would suggest you review ASTM A 217 (ASME SA 217). Look at WC1 and specified residual elements. Unfortunately, you are only going to be able to reach a Class 1 strength level. I would proceed with extreme caution on substituting a wrought pressure vessel steel with a cast product form.