It would be foolish for such a project to rely on one testing technique only (remember Hubble ?). Such a steep mirror CANNOT be satisfactory tested (in my opinion) just by Foucault. Look in ATM books for a Caustic test. And of course, endless spells of star testing (how lucky you are to have Polaris!) and refiguring are in order.
Bratislav
PS Ross null tester is a VERY good investment ... think again !