360 vs 383
I think a 5.9 should be a part of the discussion, it's still a 360 and bolts into the same spot. Most A-Bodies didn't come with a 360 or a 383, and if someone were to be looking at swapping a 360 in, the Magnum is just as much an option as a 383 out of a Roadrunner for the BB swap. If not more just because a 5.9 would be easier to find.
The option for factory roller lifters is huge to me. My brother was just talking about the cost of roller lifters for a BB...ouch.
Add that there are no low deck port EFI intakes, last I checked. Not that the 360 has that many aftermarket options, but it has at least 1 for LA heads and 1 for Magnum heads plus the OEM intake. I know most don't care about EFI, but it is an advantage to me.
I guess there is the option of raised port heads on a 383 and an RB EFI intake, but seems to me the raise port heads are out of production and expensive if you can find them.
That said, I STILL don't know which one I would pick, so I haven't voted.