The more I look at those videos, I am starting to wonder if that collision was deliberate on the part of the Kingcobra pilot. The P-63 Kingcobra and its predecessor aircraft the P-39 Airacobra are both mid-engine planes. The engine sits behind the pilot, driving the prop via a shaft that sits below the pilot, almost between their legs.
With this layout the pilot actually sits slightly forward of the wing, and that allows decent visibility immediately below and forward of the wing.
The various videos available on the web show the flight path taken by the Kingcobra pilot was an efficient pursuit curve. The B-17 should have been easily visible to the P-63 pilot right up almost to impact. And it really did not look to me like the Kingcobra pilot was trying to get back into his proper flight lane.
The point of impact on the B-17 was perfect from the standpoint of someone wanting to bring the aircraft down. The fuselage broke off just forward of the belly turret location and just behind the rear radio room bulkhead.
The more I think about this event, the more puzzled I get.