Roll Cage

[ottatyme]

For what it's worth, my day job as a project manager for an off-road specialty shop has shown me a few things with regards to cage fabrication, and I'd have ton agree that a fixed side bar is the way to go. A drop-down bar (something that bends or tapers toward the floor board near the cowl) is a great option that will offer both the benefits of stiffening the chassis, ease of entry into the car, and a measure of added safety in the event of a side impact. keeping the bar at around armrest-level, then dropping it down just past the mid-point of the lower seat cushion will provide the protection, and still allow some comfort entering/exiting.
A pinned sidebar sounds great, but is prone to failure... and the irony of being maimed by an item you had installed for safety is horrifying.
For additional stiffening, have you considered a solid body mount? We have milled solid mounts with great results in some of our trucks (elimintaing the crunches and squeaks a caged ride will sometimes offer!), and I'd think that applying this idea on a cornering street car would provide some assitional benefit, assuming you don't mind your fillings rattling around!
I hope this helped somewhat... and you've obviously chosen a great shop to have your cage fabbed... I've heard they do incredible work!