That's sick! I'm jealous of the drivetrain. I just bought a 51 Vicky but it's running a 53 Merc flathead, and power nothing.
That is one heck of a custom Merc. Beautiful car, inside and outside. You figuring a curb weight (w/o driver) of around 3900 lbs.? With that motor and transmission, it is going to scoot along the road nicely. Awesome project.