Hi all, I´m thinking about buying a 1974 Honda 550 Four, its been sitting in a garage since 1997 and the owner said it ran great before he (my co-workers in-law) stowed it away. I´ve been try to locate parts that i´ll need to get it running again and am having trouble locating some.. for instance, a back tire (3.75-18), I´ve only seen 4.0-18, can this fit on my soon to be Honda? and what about filters, O-Rings and such... are these going to be very difficult to find?