I've been playing with Guzzis for the last 10 years. I have a '71 Ambassador (my Bagger) that has lots of mods - 1000cc engine, B-10 cam, 36mm pumpers, etc. But the best mod was the lightweight flywheel/clutch assembly lifted from an 1100 Sport. Its about 8 lbs less than the standard Tonti unit, and allows much faster revving and slick shifting.
I also have a '76 LeMans which is in the que for next rebirth. First Guzzi was a '71 V7 Sport.
Google MG Cycles, Moto Guzzi Classics, Moto International for parts & tech support. Also check out
http://www.guzzitech.com/ for tips on flywheel lightening.
Have fun and if you need some help, feel free to ask!
Joe in St Louis