You are wasting your time and effort with the b-square mount. THE ONLY no gunsmithing mount that is worth anything is the fulton made one from Brian Dickicon of BDLicon LTD. they are strong, fit perfectly and are very well made.

It doesn't matter if you can use a jig or instrument to measure datums, continums, condoms or anal retentention because the tolerances in the manufacture of these rifles is such that unless you have a mile or so of adjustment on the u beaut no gun smithing mounts, you may still not be able to colimate the rifle scope to any line!

Thats why they have so big adjustment scales on the scopes so you can "dial " in your correct zero point.

I would suggest that the vertical or horizontal perfection that you ask for will not matter at the other end of the range. all that it will mean is that the adjustments will not be perfectly straight either direction but as some high-power match rifle shooters do with canted sights to accommodate cant in the shooting position, just add or subtract adjustments to suit.

Unless you are prepared to drill and tap with any number of different mounting systems that can be adjusted of datum lines then you are chasing your tail IMHO

Cheers
NED