It's a 64, (63 did not have the painted center grille), but I know nothing about the coachwork.. Notice the wrap around windshield, last used in 1960 on Cadillac passenger cars, but used on Cadillac commercial chassis through 64. This could be made from a JoHan 64 and a 59 Ghostbuster kit. Jimmy Flinstone makes a 59 hi top ambulance body that might help too.
I found some '34 Phantom II's, And the 62 Silver Cloud. Doesn't seem to be anything in between them. I've got a Phantom V in the works from two Silver Clouds, but they share nothing with the earlier cars.