Congratulations on the suburban it looks nice based on the craigslist pics. There is a Sticky on the main 1960-1966 truck page called "Making keys for the 60-66 chevy trucks" hopefully it might help.
http://67-72chevytrucks.com/vboard/s...d.php?t=630654
Basically everything from the back of the doors forward is the same as the truck except the seats, so the truck carpet should work except modification for the seat mounts, if they are already cut. Someone else will probably chime in if I'm mistaken. There are also differences in the transmission tunnels, high and low hump based on automatic or manual trans, but that is the same as the truck too. Your lucky if you have the original rear mat since they are extremely rare and are not reproduced, there is a thread here talking about them.