Imo a central feed manifold is always better than a side feed manifold, even when the distance between trottle body and runners is very short as on a TFSI engine even then its still a good design and get quite even filling. I like the design in your first sketch as it has nice transitions, plan is to get close to laminar flow, the airstream must be able to follow the radius while opening towards the runners. ideally a very long snorkel that tapers out very smootly would be great, however not practical. A restriction towards the plenum helps to get around that ( what we see in sketch 2, not as much as i think it needs, but as you said its not on scale) There are some good examples on some WTCC / lemans engines ( these are not that different to what you show here)
