Thanks all for the ongoing words of encouragement and suggestions. After a couple of days break I got back to the bench and I think i've recovered the situation to a level where I am happy enough to move on.
As I mentioned, despite my test fitting before hand, I still had all sorts of trouble getting the chin panel and nose ring to fit properly. It took quite a bit of clamping to get the chin piece on, and some shimming for the nose ring, but even then the fit was still pretty bad... In the end, I needed a bit of filler and some 'sprue goo' to get things roughly back into line. Here is what it looked like once the cleaning up was done... this doesn't do justice to the amount of fiddling and filling needed to get to this point -



After some rescribing, here's now it now looks under some more primer.


There's still some cleaning up to do, so don't look too closely.... if I was super-obsessive i'd still do more reshaping, but it is good enough for me to move on.... "that'll do", I said... this is supposed to be a mojo build after all...!
She at least now looks like a MiG.

Next, onto the fiddly bit like undercarriage, before I get to painting proper.
Cheers again for sticking with me!
BC