Side Rails:

After the rear bulkhead, fit up the large carpet piece on each side that covers all of the side rails (but not the wood floor), all the way from rear bulkhead plywood to the front upright plywood, and up along the angled side rails that you can use as a footrest. This is the toughest fitting problem, because the rails diverge in a big "Y" at the front, and it takes some patience to figure out how to get the carpet to wrap around all the contours. In the end you may have to cut it apart where the upper side rail meets the lower horizontal rail, because it could be too much of a stretch to get it all to lay flat and stay put with the tension on the material. Don't worry too much about the length and how well the side rail piece fits at the front up near the heater shelf. It might be a bit short there, but no one will ever notice it way up under the dash. Get it all cut to fit and laid (pressed) into place once before getting to the glue. Again trim the carpet to fit flat into the corners without bending the edges up. Along the bottom of the door opening the door weather stripping will ultimately cover the small vertical weld flange on the sill.

If you apply the glue to the floor and frame rails it's easier, but you may not get enough glue on to get all of the carpet to stick well. Instead, I lay the carpet out face down on a large work table and apply the glue to the back with a 3 inch wide paint roller, being sure to use enough so it will squash the glue some when pressed into place. Then before I pick up each carpet piece I clean my hands thoroughly so as not to accidentally get any glue on the face of the carpet when handling it. I then carefully pick up the carpet piece without touching the back (wet glue), and press it into place in the car. (Be careful getting through the doorway so you don't slobber glue on the car body). Position the carpet and keep on pushing and shoving until it lays down flat, the glue sticks to the base surface, and the stuff stays put without the edges coming up. The finishing touch on the sides is to trim the triangular piece of carpet to fit snugly into the area within the "Y" on the sides. This should fit tightly into the corners so it leaves no visible gap. That will be the last piece to glue in on the sides. I know of no reasonable way to block and clamp all of the carpet edges along the side rails, so you will likely have to spend some time smoothing out the puckers and pressing the edges down into place persistently until the glue sets. Patience reigns here, with the payoff being a smooth finished carpeting job without puckers.