Found a slight problem but also came up with a way to fix it

The underside of the forward fuselage. Note that the calipers are measuring the width of the fillet behind where the intake ramps go. 23.0mm

So lets compare that measurement against one for the constructed fuselage.... oh dear! it measures 22.0mm

That's one whole millimeter difference

No matter. A plan is at hand! Let's start by measuring something

this time the inside of the fuselage where it's a little bit narrower than we would like.....

19.6mm is the distance. So lets add one millimeter which is the difference we found earlier and add that to our last measurement and we get 20.6mm that the inside gap needs to be!

Easy enough to cut a length of sprue/tree/runner to the right length and then fit it in place

Gondor