thanks cattledog, that is very kind of you.
i have had a reply from Dennis Packard, i will post it below incase it helps anyone and id also be interested to see what FBG has to say.
Dennis Packard on my setup and tuning- I would recommend 4-2 needle and setting the needles at 51.8 MM. This measurement is taken from the tip of the needle to just off of the side of the brass insert on the bottom of the slide. So, in other words, you need to be on the gray colored slide material in arriving at the measurement. I don't know what kind of ajustment system you have for the power jets. If it is a fixed power jet with interchangeable Mukine pilot jets, for your altitude, I would start with a number 30. Because of your altitude (6000 ft), you will probably need to lien the needle from the 51.8 setting by approximately 1/2 turn. That means by turning the needle in the fully extended position 1/2 turn counterclockwise. Remember, the flat part of the needle always has to be facing the motor. This is achieved by pushing the needle in with your fingers and turning it to that position. In doing this, it doesn't change the tuning because the whole mechanism internally spins.
all mods are in the first post above - everything i know anyway :-)
will get back to you on the tire sizes.
thanks all for the help, really nice to have decent people willing to lend a hand