In a nutshell.
Unbolt mounts off ford seat, cut them up, you only need the inside ford rail.
Most seats have electric motors for height adjustment, I fully lowered them before I pulled off the loom, they don't do anything now. I lifted up the rear motor about 6mm as I found out afterwards it free's up the rail a lot and helps the seat slide better.
Because you using the patrol outer rail that has the slide / locking mechanism for moving seat back and forward. On the inside ford rail you need to fold up the locking slide and pin it with a little M5 bolt or it will stop you from moving the seat.
The ford rail then bolts straight into factory holes, back hole is about 15mm out, you can just bend the foot back a bit to line it up, I cut and little notch out to make it easier and tack welded it up later.
Use patrol outer rail (close to door) I made a spacer with 40mm RHS and some angle. The seat bolts straight onto this. You can just seat the seat on there and mark out the holes to be drilled.
With the buckle I used the patrol stork, I drilled out the hole to 16mm and its bolts straight into the side of the ford seat where the original one was, I put an M16 spring washer on there to keep it tight.
I used FG ute seats but all BA BF FG mounts are the same. The ute seats have the quick release fold forward lever and I'm not 100% sure if the sedans have that as well.