I read up on the vapor separator in the Service Manual and replacement is the only recommended service. There are 2-components, the manifold which is passive and would not fail, and an overfill check valve. If the check valve is bad liquid could back up into the rest of the emission components.
I would just rinse out & possibly soak in something like Evapo-Rust, install it & not worry about it. Are you planning on a correct restore with working charcoal canister? I have seen in-line check valves for motorcycles that I believe would serve the purpose.