David silver (Honda parts) keep new replacements in stock that are 475mm listed for the F and K models so your in the right ball park. What I have noticed is the diameter varies 25.5mm or 23.5mm as in the progressive race tech versions. They both fit in the 35mm tubes but give a very different ride based on your body weight/two up/handle bar set up. On my 550F2 I'm running longer tubes off a 750 with 400N superdream springs that are 495x23.5mm as I only weigh 60k. This gives me 100mm of travel (zip ties around tubes) 160cc of 2.5wt oil without the mudguard wanting to kiss the exhaust headers.Very comfortable ride.
