Archer, Looks good so far!
I am building the same kit myself (still need to start a thread and post pics).
Anyway, I have already begun to tackle that engine attachment area. Sanding
will be a nightmare if you go at it the traditional way. I decided to
attack it with chemical sanding instead.
I use a blue automotive filler but any plastic putty will suffice.
Then I took q-tips and pipe cleaners moistened with Cutex
fingernail polish remover and immediately removed the excess,
smoothing the fill to the level desired. Be careful you don't let
it dry too much or you won't be able to remove it as easily.
The Cutex is mild enough so it doesn't mar the plastic but
avoid straight acetone. That will craze the styrene.
I plan to blend the windscreen to the fuselage using the
I still have some touchup sanding to do but the method I've
described did a pretty good job of fairing the nacelle fuselage
mount into the fuselage. Did the same to fill in the gap between
the instrument panel coaming and forward area of the fuselage.
Hope this helps.