There were three series of models in 1957 starting in ascending order with Coronet, Royal and Custom Royal. The word "Lancer" just means it is the hardtop version (with no B pillar). They are all the same body and would all use the same windshield. The key word is Lancer that distinguishes which windshield you would need.
If you want more detail, you could contact Timo Tanskanen of Riverside, CA at 951 687-6579. He sources what are probably the best bubble windshields for those models from Finland (where they are really skilled at remanufacturing vehicle glass) but there are two downsides. Correctness that you can count on is not cheap and there may be a wait for getting the glass. Best to give him a call for more details. Good luck.
