ezbentley
don't penalize too much spectre. Is today most probably the most used RF IC simulator.
Take care how you measure insertion loss using transient. As you are looking at Spar, your insertion loss is a power loss, so measure output POWER/input POWER also with transient.
Anyway, if you're not interested in out of band performance of the SAW, but only at in band components, follow the suggestion to make a passive equivalent network (also equivalent in term of input and output impedances) and do your simulations.
To be sure that, in the real application, you will not have bad "surprises" follow the data sheet of your SAW, and design the proper source impedance for the SAW (that is the output inpedance of the buffer, eventually with external matching network) and the correct load impedance (that is your next stage (VGA?) input impedance.
I hope it can help.
Mazz