All or mostly original bring the most money, or restored using only oem parts. IMO restored using aftermarket parts does not add much value. I would pay more for an original bike with patina/some rust than a restored bike with aftermarket parts. A solid provenance adds value too.
Bluebook values are a joke. An excellent Z1b is listed at 12k then very good is 4500?
1975 Z1 900
1994 KX250 Supermoto
2004 KX125