2.94 gears with a four speed.

This is a two edged sword.
between adequate starter gear and comfortable cruising rpm as to NVH, and long engine life.
Fortunately, I think you have the bases covered with any and all of them, with that 408.
As a city car, you will be starting off from a stop,a lot. So the slipping clutch is a valid concern.
As a hiway cruiser for 400 miles at a crack or about 6 hours,you want to be comfortable too, so again a valid concern.
The difference from the 2.94s to the 3.55s is about 21%, so that is quite a bit. About 500rpm at 65. With 27s say the 2.94s post 2374 and the 3.55s post 2866, and the 3.23s post 2608
Obviously the 2.94s are the way to go at the hi-way end.
At the other end we have then 2.94 x 2.66 =a 7.92 starter gear.This is barely adequate for a teener, barely doable for a stock 360, and anytime the engine is cammed up, this is a bit of a struggle. Manual trans SBMs typically like from about 9.5/1 to 11/1 depending on how hotted up they are.
You, on the otherhand, have a 408. So depending on how soon your torque comes up to 3602bbl-cam level, will depend on how tuff 7.92 is to get going with.
But there is another option; the 3.09 low gear that came in the early 273 boxes. This will get you a 2.94 x 3.09 =9.08 starter, and is 16% stronger. Now 9.08 is pretty close to 9.5(what I earlier called the minimum), and I'm willing to bet that your 408 will do very well with this starter-gear. So this seems like a good solution.
But lets look at some driving situations. In relaxed driving, I like to outshift each gear at no more than 2800. For you, the MPH equivalents would be;25,40,55 and77. That's pretty sweet for a 360, cuz in each case the mph is near to a common speed marker, and at 2800 the little 360 is making pretty good torque already. Your 408 will have no trouble with this situation.
Next consider a zero to 60mph blast. Well, this will be a tic under 6800,again near perfect for a hot 360 which may be done at 6000 and and is well on the way down the power-curve. I don't know about your 408, but the other two choices (the 3.23s and 3.55s) would force a shift for sure.So again you are in good shape. But if you have to shift at say 6400, this will be about 56mph, and the Rs will drop to a tic over 3900. So for a 360 that would be a struggle to pull the next 4 mph.For a 408 I cannot say.
Now let's look at track time; 6400 at the top of third with those same 27s is 125mph. With the right power to weight ratio, this is probably in the ballpark. Just don't expect much in the 60ft.
Still this is probably as nice a multi-purpose combo as you are gonna find. It is always easier to make a strong street/stripper with more cubes, and the 408 is about as good a combo-engine as it gets; with the possible exception of a well-thought out 383/400.
So for me, I would go with the 2.94s and 3.09low. If I needed a lil more get-go,lol, you have the chunks in about 10% increments.
If the hi way cruise is a once a year deal, I'd probably go 3.23s.
And if there is a bully in your neighborhood, the 3.55s
But, I gotta tell ya, I've never owned more than a hot 360, so I'm arm-chairing it here.
One thing I have had is double overdrive and 4.30s. this gave me a 2.38 final drive and allowed 85 = 2500rpm, and a 3.09 x 4.3 =13.28 starter gear. This was wild! With 325/50-15s the launch was baaaad!When it stuck :(