Thanks Wil.. happy to send you the full detail on the floor mods if you'd care to review..? Better to modify at this stage than after the interior is installed.
The mods were more comprehensive than just the quoted extract as I didnt want to bore the masses with all of the detail..
I ended up using 6mm wall, not 5mm for the main RHS rail. The end caps are 5mm on a 4mm wall chassis rail as noted.
Each junction of the 4" tube to the RHS is reinforced with a 20mm web plate and or joined to additional sections at the firewall and rear bulkhead.
Included also are the side impact / reinforcement measures with 3x50x25x3mm RHS uprights each side under the sill, which is upgraded from a 25x25 to 50x50 section. The downtube from the bottom of the A pillar is now also upgraded from 25mm sq to 50mm sq x 1.6mm wall, with a V section brace to the main chassis rail in 40mm roll cage tube half way between the firewall and the suspension mounts.
The transmission tunnel has been braced with 50x25 sections connecting it to the firewall and the rear of the seating area has an increased 50x25mm horizontal section and a web supported cross brace in 25mm sq connected to the dropper from the 4" cross rail on each side.
The firewall and footwell structures have been rebuilt with 50x25x1.6 and 25x25x1.6 to form a cage, with diagonal bracing on 3 sides and the top, These are bonded and riveted at 50mm intervals with 3mm AL sheet. The floor area in the main cabin is also now 3mm steel, welded all round, rather than 0.9mm Al sheet.
The roll cage has an additional brace to better suit a RHD vehicle and a crash bar has been added to the rear, but no diagonal bracing to the top of the rear bulkhead.