As I remember reading, the 383 2bbl was allegedly a favorite engine of many Chrysler execs. The 383 will a bit less off-idle torque, but the shorter stroke like, personally. With the 3.23 and your tire size, it should run about 25mph/1000rpm on the highway. Going to a 2.76 will make it more like 28mph/1000rpm. With a somewhat "normal" cam, figure on about a 2800-3000rpm torque peak, which would be about 75mph with the 3.23s.
That "favoriteness" might have been related to a 383 2bbl being a bit more saleable to the general public, I suspect. Bigger than a 318 and not as thirsty as a 440, where the 440 4bbl was not standard.
Look at all of the things you'll need to alter with a B/RB where a LA currently is. A stroker 408 LA might be a better alternative. Not as much visual "pop" when the hood is openned, but MUCH easier to change spark lugs on.
Back to the orig question, I'd go for a slightly-enhanced 383 with AVS2 myself. Even if it might mean using a factory stock cam, a "Road Runner" torque converter, a good dual exhaust system with good headers or HP manifolds (if possible), and a modern fuel and ignition system. Keep it simple for best results, to me.
Just some thoughts,
CBODY67