At time = 5:24 within the following video you can see two cut-outs in this original '67 carpet and I don't know what these cut-outs are for. It looks like the passenger side, front, but I'm not sure.
That is the drivers side carpeting and the cut-outs are for the column and I believe the gas pedal. I just did these a couple months ago on my Coupe
I did have an original (67 Cougar) front carpeting in my car so I had the "template" of that carpeting to use.
The non-mass backed carpeting is what I used, it had much trimming involved. The Coupe had a different finish around the rear seat trim than what you are dealing with. Mine had a vinyl edge where it meets up to the 1/4 trim and it doesn't come on the replacement carpeting either, leaving me to have it sewn back on. I will be taking my rear carpeting to an upholstery shop, just down the road to accomplish this, once I make that final cut-in. I only did a basic test fit with the seats, seat belts so far. I am waiting on the dimmer switch and final trim till after I steam the wrinkling and such fully out. I can appreciate that the mass-back carpeting might be easier, but as for me, I like the original type better because it feels more like the right stuff going in. There is a bit of work, but patience is the key. They seem to give you enough material, they just didn't "finish" the job right, like the OE stuff was.