Depends on the registry. Strictest says 90% QH. By this no your horse isn't. One of the registries allows 25% TB blood. This would be the most allowed. There are/were five different registries with differing requirements. The FQHA (90%) will also allow an appendix registration for those horses that are between 85 and 90%. Your horse is on the heavy end for racing Qtrs so wouldn't qualify for any of the associations.