http://www.megacyclecams.com/catalog/page57.pdf
http://www.hagon-shocks.co.uk/main1st.htm
I've seen prog front springs on ebay, try "Wurth" mainly from germany, but I'm sure you can get them in USA.
HVC cycle may have them
high rpm on idle is too lean a mix and either compensate by richening the idle mix on the carbs or they need a good clean( pref ultra sonic)
I'd try ebay for gaskets, partsnmore do them for $45
drewps