Try Kais suspension in Manchester. My wife is a little vertically challenged and this company proved very helpfull. She has a fireblade and wasn't heavy enough to get the suspension working. Decreasing preload etc upset the suspension.( Perhaps more noticeable on a sports bike ) What they did was to use the original shock and modify the internals to shorten it, ( don't exactly know what they did ) weighed the wife, and then changed the spring so that it was more in tune with her weight. Just to level things off they then dropped the front forks through the yoke by about one centimetre. Result is one lowered blade, personalised suspension set up, and only one new component. All done on a Saturday morning. All that was left to do was shorten the side stand. I'm sure there is someone local to you who can do this.
The only difference for the Gs would be to shorten the front shock, rather than drop the forks through the yoke.
The guys are suspension experts. They do the set up for many racers, and judging by the bikes outside are slightly more off road biased than track racing. Can't remember the contact details, but I'm sure Googling them will be OK.