I think you are wasting your money to hire out a 737 or any kind of jet sim.
If you have flight sim, use it if it makes you feel more comfortable, but lets be honest here, in a sim evaluation, they are not looking for how well you fly the jet, because you may never have flown a jet before, or that type, they are looking for how quickly you pick things up, how quickly you learn from a mistake, how quickly you get the hang of the ils, how well you work as a team with the other guy, how well you make use of information available to you.....the list goes on and on.
But to think they are just interested in how well you fly the plane is naive.
Remember, if successful, they are going to send you to a very expensive simulator and teach you how to fly the plane.
Be prepared, but there is more to passing a sim evalution than just knowing speeds, power settings, pitch attitudes and call outs.