59-60 essentially use the same floor from the firewall to the rear bumper.
Minor differences in the rear seat footwells and the under the rear seat panel (under the panel in the bed), but they are interchangeable.
Changing the floors from the firewall to the rear of the doors is pretty straightforward.
They are spot welded to the top of the inner rocker and are not too bad to remove.
The "under the rear seat pan" is a different animal as this was already in place before the back of the cab was welded in. If you are not interested in removing the back of the cab, you could get the new panel and piece it in place without disturbing the cab panel.
Might be a good idea to get your floor panels first.
available in pieces from the toeboards back, but nothing to replace the area under the seats or the tunnel itself.
Full floor is available from the toeboards to the rear footwells, but would have to be cut up to get that piece into the car.
Not sure if that under the rear seat panel is available-----was not when I did my car, so I had to appropriate a section from a 60 Impala.
Floors are the same in the Sedans, wagons, hardtops and are not ElCamino specific.
Wagon and ElCamino are only slightly different from the rear axle back.
Wagon will have a spare tire well or footwell for the 3rd seat, where the ElCamino
panel is just a flat piece of steel (basically).
If you can get good floor pieces from a junkyard 59-60, go for it---probably save some money.