To respond to NJRacer510 and TRMIV,
My driver has the same seat in his car, he's 6'4". We modified the side tabs (no rethinking due to your post) and mounted the seat against the floor, same spacer type setup as you NJRacer510. The difference is we did tie the upper "halo" piece to the frame by welding a piece of 1"x1" tubing across the car, underneath the lower halo rib (where the stickers say "mount here" ) The halo is bolted to the 1x1 in 2 different spots, and the tubing is welded to (I think, I'm away from the car right now) the down tubes (c-pillar tubes). We also rerouted the shoulder belts differently coming up further than they had been using an existing bar.
Apparenty we should have mounted the halo differently.... using aluminum brackets or something.