As the underfelt is black side up, photos do not show anything of value.
For the underfelt I start with the floor below the seat, cut holes for the seat runners fixings using a flat bit drill to loosen the weave up, then scissors to get the right oval shape.
Then I do the rear bulkhead to the engine/seat back. Just the two side bottom bits, there is none on the big side to side part covered with the hardboard/plywood panel.
Then I do the side for the transmission tunnel. You have to cut a round hole for the seat belt to chassis centre bolt.
Then the strip below the door.
I cut the big pieces first, so there are plenty of off-cuts for the smaller pieces down the footwell.
I use spray contact adhesive on both surfaces, and wait about 2 mins before fitting.
The hard part is getting the holes in the right places for the seat belt mountings, especially if they are stuck fast in the sill below the door.
Use disposable gloves when gluing as it gets everywhere, and you have to use petrol to get the glue off your hands. Add the smell of the glue sniffing, and you get a headache.
On two of my chassis off restorations, I have had big trouble re-fitting the bolts for the seat belts into the centre chassis. Despite the front and rear bolts lining up to secure the chassis to the body, those two holes just did not line up. I had to over drill the holes to about 15mm, and then put a tap into the chassis tube to get the thread clean. I used wedges from underneath to push the fibreglass of the tunnel away from the chassis to give a slight gap between the aluminium bobbin set in to the body, so I did not drill into the threaded tube welded side to side in the chassis which is the centre anchor for the seat belts. Those two bolts now go in easily.