The CCG parser has been extensively evaluated elsewhere (Clark and Curran, 2007), and arguably GRs or predicate-argument structures provide a more suitable test set for the CCG parser than PTB phrase-structure trees.
clark and curran (2007) shows that converting gold-standard ccG derivations into the GRs in DepBank resulted in an Fscore of only 85%; hence the upper bound on the performance of the ccG parser, using this evaluation scheme, was only 85%.