@Benjamin My older sister lives in Tampa - Please keep her down there. 
If you're getting a Beck, ask Carey if they can modify the rear window with a zipper around the sides and top of the window itself so you can un-zip it and drop it down. If you leave it up, especially with the side windows out, the top tends to buffet in the wind as you're moving and drive you nuts. Unzip the rear window and the buffeting stops.
The only 356 I've ridden in with A/C was Tom Marantz's dark gray 356 coupe and it was really cold. He had set it just below mid-range on mid-90's days at a Carlisle meet and it was chilly in there. Yours should have little trouble keeping up, plus it's a very effective defogger. Probably enough cold for top-down driving when it's hot, but I have no experience there.
I drive 2 - 3 months of the year with the top up and side windows in on my Speedster (I'm up in Massachusetts). I wear "Ear Peace" ear plugs so the noise, while different top down versus top up, isn't all that bad - much of it is carburetor intake noise and not enough to drown out the radio but it's best to stop and shut down the motor to take a phone call. ALL of that depends on the exhaust system ordered and how loud it is.
Visibility: Yes, there are blind spots - they're pretty big. Ask Carey to install convex mirrors on both sides (door or fender) - those should help a lot.
You cannot see an overhead stoplight when you're first in line because the top obscures it. Get one of these for $20 bucks to see the light - Mine works great:
It looks like this below (I circled the stoplight obscured by the top). It doesn't affect your vision out of the windshield (it hangs down about 2") and was OK'd by Applus here in Mass. They're the "We don't approve anything we don't like the looks of" arm of the Dept. of Motor Vehicles and are a lot more strict than anything in Florida.
Hope all this helps. Gordon