Offhand, I would say no, not if you size your single injector properly, unless cost is a factor, and it would be cheaper to use two smaller flowing injectors rather than one large flow injector. In your measuring, did you account for fuel hoses and electrical connections, or just physically squeezing in an injector? What injector did you use as a baseline?
I still think hiding your injectors in the plenum is ideal, from a practical AND from a functional standpoint. You can have a straight shot down the throat of the carb, nobody will see it, and there is plenty of space. You are going to need a plenum anyway, there is no hiding that, so you might as well make full use of it. This would work pretty well with a side feed injector like on an SR20 motor.