I would agree with that as best case scenario, but his car is near 3400 with him in it, so....12.35?
The problem is info that is missing about camshaft (hyd or solid)so no one knows powerband or ideal shift point.
Op has stated he will be happy under 13s. I think he'll be happy.
(If a hyd cam, I'd shift at 5500, solid at 5800-6000)