Darren, you are working hard to make a tired looking airplane, but hey, with that nose art who's gonna see anything else? Looks good.
I have one coat of grey primer on K5054, and some Mr. Surfacer 500 on a couple of wing panel lines that I scribed too wide, but I am making progress. The engine intake air scoop is different, recessed a little and located a bit further back, and then there is another scoop that covers up the back of it, that's all done, and I also inset plexiglas on the wing tips, sanded them down smooth and polished them, because K5054 had that kind of position light arrangement. Doing this is starting to feel like I brought in the Spitfire, jacked it up, and changed out everything but the overall outside shape!
Greg, I make a special sander to do inside curves like the wing roots, I just take a wooden dowel of the right diameter and attach sandpaper with CA glue, rolled around it. I use a pretty coarse grit paper and don't press very hard, then touch it up with a finer grit. I put Tamiya tape on both sides of the sanding area to keep collateral damage to a minimum. It's usually best to put the tape down before you apply the putty. At some point I came to the brilliant conclusion that the excess putty I don't put on is excess putty I don't have to sand off!