I would be hesitant to put a 4-barrel carb on a low-revving, smallish engine like the 235. With an appropriately sized and tuned carb, you could get driveability that's just as good, with a little more power for getting on the freeway. I would recommend a 390 cfm Holly, or a small (I think it was 425 or 450 cfm) Rochester Quadrajet.
The Rochester has very small primaries, so it really does provide responsive driving at lower rpms. The secondaries are absolutely huge, so you'll never run out of air with your foot planted. The smallest Quadrajet came stock on the 4.3L V6 (262ci). It's about 11% bigger than your straight 6, and it winds up a little higher, but I don't think the stock carb from it would be absolute overkill. I always promote Quadrajets, because I think they've gotten a bad rap. The Holly is a good choice, too. Both of these carbs are progressive, vacuum secondary, so you shouldn't be over-carbureted, even if you have more than you need.
I can't speak regarding multi-carb setups. I think they're sexy as hell, but I've never worked with them, and they scare me. It seems like if they're progressive, and you don't drive like a [censored]-off teenager, they should still serve you well.
My final opinion would probably be to go for a two barrel. These trucks were originally designed to be driven like tractors, so they're rather undercarbureted from the factory. Stepping up a notch without going overboard wouldn't hurt anything and will probably give you a noticeable boost. Once you've got your headers I think you'll really reap the benefits.
