I am almost complete. Check the pics and the vid.
The model with a weight I got from a fishing tackle shop. I'm not sure why I didn't think of this sooner instead of spending all that time making my own weights.
Front view of the gear
Here I had tested using springs but it was still too sharp a reaction. I also realised that I could control all the limbs and the head with one control lever so I now only have one for the head and limbs and another one to operate the hand.
Here is the reduced lever set-up with the weight. I have used a slightly smaller weight as this one was too heavy and not needed (I think - I'll need to add the limbs first and see how they react).
All I need to do now are add the wires for the limbs and make a few cosmetic changes, add a lick of varnish and it'll be done! :)