Thanks to everyone for your encouraging comments. I've been sanding the flaps and wings to get the flaps to fit in a deployed position and to thin out the leading edge at the slats to make it look more correct. I've posted a couple of shots of progress.
Photo 1. I know this looks like something from Dr. Frankenstein's laboratory but it's a dry-fit of the lower wing assembly, to make sure that the nacelle backs fit into the main nacelles. After thinning down the nacelle walls and sanding the top of the back nacelle, they fit rather well, giving a flaps angle of about 30º. The next task is to work on supports that will connect from the flaps to the wing, for strength and holding them at the right angle.
Photo 2. The upper wings, again showing a dry-fit of the nacelles. It seems a good, tight fit, and hopefully after sanding and cementing, there should be little or no filling required. Backs still need to be added to the flaps to fit into the wing interiors.
That's it for the moment. More soon.