Well after a suitably long time demo-ing shafts and flexes from all major manufacturers I have finally found my shaft. A UST ProForce ATR65, has a soft tip rather than the normal Proforce shafts but what a shaft, powerful, straight can take being swung hard if necessary.
Tried this shaft in a couple of heads both in regular and stiff flexes and finally toook the plunge to have it put into my 983K (44 inch, reg flex because of the bore-through design). Collected it last night and the first range visit was extremely promising and brilliant fun that only comes from hitting the driver well. straight shots landing at 230-240 yards and rolling easily to the end of the range. Not bad for range balls and a less than dry range. Roll on the firmer fairways.
Seriously considering putting the same shaft in my TM Rescue #2.