Found a 1957 Custom Royale Sedan. near show. what should i look out for?

55 owner here. These cars are a different animal than the 60s era unibodies. Yes, the drum brakes suck. I just did a 4 wheel disc brake conversion......

Have a good look at the frame, body mounts, any rubber part including engine and trans mounts and drive shaft boots. Check for frame cracks around the steering box mounts. 5 on 4.5 wheels, LH thread on the LH side. The wheels are held on (at least in 55...) by bolts like a VW, not studs and nuts. There may be a pilot finger that fits a hole in the factory wheel (again for sure on my 55) that needs to be removed if you plan to install aftermarket wheels.

Check the wiring....... likely there is the old cloth insulated wiring which gets old, brittle and breaks down.

If it has not been done consider putting in a more modern dual reservoir master cylinder and disc brakes. I used a rustyhope disc kit and a ford explorer rear end. I think you will find that park and the e brake are both handled by a drum brake on the trans output and it will have ball and trunnion u joints.... which in my experience are troublesome. Another good upgrade is to a conventional 727, driveshaft and differential with e brake.

Very nice lines on that year! PM me if you want more details.