The MS are identical to the VAC ones - and I mean IDENTICAL. I should know, I've got VAC ones in my racecar. My bet is that MS took a set of VAC mounts and "reverse engineered" them, making their own pieces.
That said, they offer pretty low seating position. For the lowest possible setting make sure you mount the seat as low as it will go in the side mounts - additionally, and I only recommend this if nobody other than yourself is ever going to drive your car, you can mount the side mounts directly to the floor mounts (e.g. don't use sliders). Your seat will be fixed, but it'll remove another inch of height.
***JEREMY DAVID LEONARD SMITH (1987-2008)***