There are a number of visual organizational and visual integration tasks that are closely correlated with extent/presence of brain injury (RCFT or Rey-Osterreith is another one, beloved of neuropsychs).
Another instrument for assessing motor-free visual spatial ability is the MVPT-4, usually given by OTs.
His alphabet fluency may or may not parallel his Cd performance, as it includes retrieval fluency/automaticity, which is one of the core deficits of dysgraphia, as distinct from actual fine motor coordination. If measures of motor coordination (which may include Cd) are good, but alphabet fluency is below average, that would suggest that it is not (or not only) motor coordination per se that is the challenge, but automaticity.
