TBH with you, it was a bit short
And I think it needs a bit readjusting still...
https://www.supercars.net/blog/1965-ford-gt40-mark/
According not just to this article, it was capable of hitting 320+, and with that 315 setting it cannot hit 320+ and gear ratios are approx 1.00:1, 1.29:1, 1.70:1, 2.50:1.
Cheers...