Well another week and actually made some progress this weekend as the weather has gone back to normal.
I discovered I had a problem with my choice of donor kits in that the Transall tapers to a narrower cockpit with a more angular flat faced windows, the 681 however is more rounded and wider conforming more to the diameter of the fuselage. After checking out various possible donor kits both in the stash and on-line I decided that the VC-10 cockpit windows were nearest the Mark so after a polite email to Anigrand I managed to procure a replacement canopy from their VC-10 kit.
So this last weekend I taped up the interior loose fitted it to the fuselage and taped the two halves together. I was in a Catch-22 situation as I couldn't assemble the cockpit till I knew the canopy would fit or else all the interior detail would be lost to PSR debris and dust and thus I couldn't join the fuselage whilst the interior needed to be finished, thus copious amount's of Tamiya tape to strap everything together to gauge the fit of the canopy. Well first look and it did the job, it looked right in profile and fitted just about at the front windscreen, however it overhung the rear corners of the cockpit by a good 3-4 mm each side

. Its resin so it would snap if forced and that gap couldn't be made up easily as it showed just how much taper there was in the cockpit shape, so out with the plastic card to build up sills for the canopy to sit upon in the corners as the top edge and front edge were OK. Then it was a case of back filling to blend with the fuselage followed by Milliput and plenty of PSR.
I can now happily say that the canopy fits, just a bit of fine adjustment required at the front, and it has the look and feel of the 681 now

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I also managed to work out a basis for my tail fin, as the 681 has quite a large and distinctive tail fin that others don't match, then an idea came to mind and I dug out the spare wings I had from a B-52 scrap kit I once had. They were close if a little too big but the lower halves with the flaps missing were almost perfect, so the two lower inner wing are now being worked upon to create my new Tail fin.
Still lots to do to sort out all the bits I need, the Fuselage needs work at the rear to change the door format and tidy up the tail cone shape; then I need to get to work on creating and moving the wings box forward and filling in the resulting gap behind the wing, but that comes once the fuselage is joined together.
I only have two engines almost built with the other pair in need of starting. I need to do all four engine pylons the Fin top fairing for the tail planes and of course the rather large sponson's for the undercarriage.
Ps to follow