Hey Mrclubike that's pretty clever, well done on your fabrication! I reckon if you use your bike as an adventure bike it's a fantastic idea, after going into the bean can I was thinking how susceptible they might be to a stream crossing in high flow, which I've done before with no problems (touch something wood here!)
I'm hoping that mine never goes 'kaput' on the road... But was pretty nervous whether the whole thing would work again after a couple of rounds taking it off and messing around with it.
I've ended up putting the old springs back on, feel the bike is a bit more sprightly with them on and haven't got the original problem anymore either. Still would like the revs to come down a bit faster than now but better than before. I straightened up my spring anchors, I think they may've bent in perhaps with age and amount of km's (it's sitting on 186 000 km), also possible the springs have been replaced before and stretched since. With the straightened spring anchors the old springs are more stretched at rest now than they were. Advance starts a little later, at approx 1700rpm and still stops at 3000 with the springs being stretched a bit further at rest. I'm OK with it.
I think I bent the spring anchors down so far for the new springs (through the inspection window) that the springs were rubbing on the weight arms which caused further friction but with five days to go before a trip I'm not messing around with the new springs any further at the mo.
Second time around and with better punches it was much easier to get apart and rebuild the bean can, so I'd give it a novice pain in the a... 7/10 rating for risky work!
Oh and it is possible to bend those outer spring anchors through the inspection hole, nice idea Mrclubike. Cheers.