5.7 Hemi Duster
Probably need to decide what you want first. The BB will be more old school (and cool) but the 5.7 will be more new school (and cool as well).
You can carb a 5.7, but it has to be an '08 and older as the MSD ignition setup only works on those. And there are only 1 or 2 options for a carb'ed intake, if that anymore. Add that the '08 with a carb will be down a good amount of power to a later 5.7 with EFI, VVT and variable runner intake tech. So, in my mind, pulling the EFI off a 5.7 is a mistake.
At the same time, adding EFI to a BB can be some work if you run a low deck motor as there isn't an off the self intake that I am aware of. The tall deck motors have kit options (I think), but a low deck will be a custom intake. And when you are done, you still don't have the option of VVT and SRV intakes like the 5.7 does.
So, probably best to decide which direction you want to go and then pick the motor that fits better.
Just some thoughts.