340 cam

I'm gonna buck the trend.
I would NOT pick any cam until I knew the exact Static Compression Ratio. Doing so, IMO, is a recipe for disappointment.

My choice
would be something on a 108LSA and whatever Ica jumps the Cranking cylinder pressure up to just under the detonation zone with whatever gasoline you intend to run. Solid or Hydro in this application, I don't think is gonna matter much.
If it was me,
I'd set it up to run max pressure at WOT on 89 gas, then run a two-step timing curve, delaying the all-in timing to say ~3600, but bringing the first step in, as fast as possible, then put a smaller than usual 4-bbl on it, like a spreadbore. If I got detonation, I would give the carb an airgap intake and fresh air. If I didn't, then I'd try 87 gas.
Why the 108Lsa?
cuz if you run headers, then size for size, the 108 will give you more overlap which with headers makes more power thruout the rev range.
But if no headers then overlap means nothing except that the intake is closing sooner and your bottom-end will be stronger.
I would choose a cam with a great deal of Power duration to suck every last joule of energy out of the expanding gasses to get as much mileage as possible out of every pound of gasoline, because the price of gasoline is never gonna get cheaper, AND
nothing is worse than not being able to afford to drive your hotrod, cuz it sucks gas.
That's what I would do.

3.55s will get you a crappy Second gear;
3500= 49mph/ 65=4600
so there is NO good reason to stick a hi-rpm cam in this cruiser, You need a cam to cover 3500 to 4600 and nothing more; crap a 318 cam has that covered...........