At the moment the injector ends sit 10-15mm below the top of the bell mouths, I think they should be at least flush with them if not above. From what I understand you want to try and get them as far as you can from the combustion chamber to get the air and fuel mixed as much as you can, but not too far above the bell mouths that the fuel isn't getting drawn in to the inlets.
Let's see what people come up with
