Parts for Yamaha Passola SA50 (11/1979)

Question

I am trying to get an old Passola back on the road for my kids. It has not been going for about 10 years. The fuel system has corroded up. I am looking for a fuel shut off valve assembly (mounted on frame) and carburettor needle valve and gasket set. Where do you suggest I start looking for these parts.
Thanks Brian