Thanks again Paul, your input has been extremely helpful, and I've picked up a lot of pointers from the stuff you've posted. One of the things I noticed in the caption to the pics was the fact that the TBM1-C had a vertical radio mast, as opposed to the earlier, raked one. I wouldn't have known if you hadn't posted that particular page from the book - marvellous help! At least one of your latest pics will help Lucke too, as he wanted pics of the wing-fold details. What a fantastic forum this is! I'm more accustomed to modelling aircraft I know well, and mostly I've had first-hand experience of. I've only ever done an Avenger once, in 1/72nd scale, OOB - and that was about 43 years ago - so my references are pretty thin, and all the help here has been most welcome.
Anyway, after about eight more hours work, I think I've managed to save the warping problem, although there's still a bit of remedial work to be done. The fuselage was joined, starting the glueing at the tail and working forward up to the upper nose joint, and keeping the fuselage halves tightly taped until set, as shown in PICS 1 and 2, the latter also showing the sanding back of the CA glue used as a filler for the upper nose joint.
The problem area around the lower nose on the port side was also superglued and clamped, as shown in PIC 3, but a trial fit of the cowling showed that some re-positioning and sanding was needed, so the joint was separated and the parts re-set. A further trial fit of the cowl indicated more sanding was needed around the forward bomb-bay bulkhead, PICS 4 and 5.
Meanwhile, the engine was assembled and painted, using Xtracolor 'Oily Steel' as a base, before a wash was applied, followed by some light dry-brushing and detail painting, then the crankcase cover and ignition harness etc added. I considered adding some scratch-built detail, but the kit parts, which are mostly covered by the cowling anyway, are a good enough representation of the R2600, as shown in PICS 6 to 8.
Pics 9 to 11 show the engine in place, and the cowling now fitting more or less correctly, although a small amount of 'liquid' filler will be needed to tidy up the slight gap on the port side, which looks bigger in the pics than 'real life'. Once all the joints have been cleaned up, any erased detail will be re-scribed. It's only just visible in the pics, but the cowling fasteners, engraved into the kit parts, have actually got the slots engraved into them!
The final pic shows the progress to date, but there's a heck of a lot more to be done on the main assembly, not counting the bomb-bay interior and doors, or the landing gear etc, before the main painting can be commenced.
Thanks again to everyone, and particularly Paul, for the assistance, kind words and encouragement.
Now, I'm going for a couple of hours kip, as I stayed up all night trying to correct the bl**dy warped front end of the model!