I like the cage/tub in the driver's seat area. I assume there was a lot of cursing, half-math and dry fitting to get there?
To answer another Captain's question:
The floor was originally very rusty and not really connected to the rocker on the driver side.
After seat position was decided (distance from wheel and control centering).
Temporary mounts made from angle stock and round tube were created to confirm seat angle and position. Marks were made on the floor to represent mounting position (our seat was on a slider, so max back position was against main hoop in roll cage). Our seat position was too high and would not have passed Tech, therefore the floor must go. I used a digital angle finder to set seat angle in relation to rocker.
The tube (1.25" x .120") that is welded to the rocker panel (upper right corner of picture) extended across to the passenger rocker panel, because the floor was so bad, to support the front of the seat. While the two tubes that parallel the driveshaft support the sides of the seat. The seat is bolted to two pieces of 1" x 1" x .125" angle that have nuts welded in them, the tube between the mounting flanges is for the anti-submarine belt. Originally all the tubes were straight, but as the seat was lowered more and more to pass Tech and for visibility, the tubes needed to be bent to still be able to weld into good metal (you can mock it up with scrap tube and add bends at final install). The angle of the side rails is the same as the original mock-up, find something in the car to measure front to rear position and use a plumb bob from points on the roof if necessary.