Carbide 300r would be a better choice compare to spec 02/03... the spec 02/03 is similar... i have a spec 02 my self and the issue for spec 02 is that the choice of compatible air cooling heatsink is limited due to the max cpu cooler is 157mm..
unless you would want to used closed loop cooler.
i bought the spec 02 because of the looks & have a window...
as for the air flow the Carbide 300r have extra fan on the side...
in my opinion, as long you have good fan to pull the air in to the case, it should be fine..