On further digging through the documentation I have, I have found in the Tony Hayes (may he RIP) publication "Thruster Two Seater Identification Guide For Owners and Inspectors Second Edition 2003", some information on washout. I offer this as information only as it does not specifically relate to single seat Thrusters, such as the T85SG that the OP here, Tony, is rebuilding.
On page 42 under the section GEMINI SPECIFIC TECHNICAL INFORMATION, Pitch Instability Contributing Factors, 5. Changed Wing Wash-out. I quote "The Thruster wing has neutral wash-out when static(i.e. the under surface of the wing root and wing tip should be at the same angle). However wash-out is built into the wing support design and is adopted when under flight loads." end of quote. The section goes on to explain that changing the lengths of rear lift struts, and incorrectly tensioned flying and brace wires can deform the wing from prime design under flight loads. No mention is made about degrees of wash-out or other specific measurements.
This information doesn't bring Tony any closer to the answer he seeks, but is extra information on washout design on the Thrusters.
Perhaps contacting Kay Hayes, Tony's wife, may uncover some specific documentation on this.
Pud