Alex, I have been looking at the 400 action with regards to the 12 ft/lb conversion, it is a simple one as far as 10m rifles go with no machining of the action necessary.
As for which model, I would always go for a wooden stock as it requires less heat to warm up than an alloy one, I know you have experience of alloy stocks so I suppose it comes down to your personal preference.
But I like this one!
That one is ambi with the cocking switchable to either side.
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.