Krusty -
A quick look as some pics on the web seems to bear this out.
Every highback has the 2 cannons + 4 ports.
Every bubbletop has the 2 cannons + 2 stubs.
Unfortuneately the 'e' wing designation denotes 2x20 + 2x50 +1000lb bomb load.
There was no provision for 4x303 by 1944

notice no access panel where the 303 would be.
Compare to 'c' wing (I know Dan)
Access panels clearly visible.
[edit] Yup haven't found a single pic that can definately be identified as a 16 that contradicts this.