I have kept this JohnDeere manual for 30+ years.
I will try posting a picture of the carb jetting page at various altitudes and temperatures.
The Liquifires used an engine from Kawasaki that was nearly identical to the Invaders.
They used the same style and size Mikuni carbs.
John Deere did jet the Liquifires slightly different from the Invader, but pretty similar.
It looks like they recommend dropping the main from 150 to 130 when going from sea level to 4000-8000 feet, and a slight reduction in the Power (econo) jet also.
This could give you a start...perhaps someone on here has some experience with the Invaders at altitude.
You might also consider removing one washer from each of the 3 ramps in the drive clutch to help it be able to still let the motor rev up to its normal shift speed....just remember to remove exactly the same washer from each ramp. If your Invader is still stock, it should have 3 washers on each ramp, 2 on one side, and one on the other side of the ramp. So, to keep balanced, you could remove 1 washer from the side that currently has 2.
Rick