Yes, Chester did leave his research with the Castor Association of America (CAOA). The email address is caoaboard@caoa-gen.org. The CAOA has an archives accessible to members by appointment or inquiries may be made to the Archive Coordinator (currently Patricia Caster). The membership fee for new members is $20 annually. Another benefit of membership is the quarterly newsletter.
The CAOA surnames are all derivatives and spellings of Caster such as Custer, Koester, Custard, Kester, Keister etc. etc.