1st off, you need to break the sled in before getting a clutch kit. My stock clutching seemed off at first, but with over 500 miles the motor continues to get stronger with each ride and the stock clutching is fine. I would honestly wait at least 500 miles before buying a kit, and if you have the patience even 1000 miles. I tightened the secondary spring 10* which made a big difference in the backshifting but the stock clutching really does seem fine. But it's your money. The only place I'm aware of that will have a kit soon is Ulmer Racing.
The only thing different between the low and high elevation setups you listed are the weights and primary spring. A second set of weights set up for 8-10k ft. and a GWG spring should be all you need.
