Get on a lead sled site and you will probably get responses and tips. Different grills have been used for years with 37 LaSalle grills in 40's era coupes, Desoto grills in the 50's, and 54 Chevy grills with extra "teeth" in about everything. Mercury and Pontiac were also a favorite and of course you had to have Packard tail lights. As stated it can be done but lay everything out with cardboard and masking tape strips where you can then squint your eyes and visualize the finished look. Much cheaper and easier than starting with metal. You might want to do a search on Sedan Delivery's and see how they strike you.

Evan