I had one like that, original owner H. Hughes, original color was silver-blue.
Is this the same car?
The 390 with the Hydro does just fine. A limo of that vintage will smoke 'em.
I swapped a '59 limo to 400/700R4, and I'm not sure it was worth it. (I still have the 60k 390!)
I can tell you the 472/500s won't go without a lot of surgery. Forget that option, the oil pump is smack in the middle of the crossmember.
There was a factory-optional dual quad, but you probably won't net any advantage in such a heavy car. I would go with a modern cam grind though.