On the grade without researching I don't remember but you are always better off being a little harder than softer, the only thing it will hurt is your wallet. On supporting your engine if it's a factory pan and not a cheap aftermarket/Chinese one I have never bent one supporting it correctly with the right size/piece of wood on the lower part of the sump in fact I have had many Pontiac motors setting on a cement floor on their pans without problems. This is it's strongest point where it goes straight up to the block forming right angles just watch out for the drain plug divot. Make sure you unbolt both motor mounts and if your fan is mounted be careful of your shroud. Because there is a bolt and not a stud you don't have to go very far to sneak it out just go a little and try and go a little more if it won't come. As far as scratches just use a little cardboard between your wood and pan. And don't sweat it, crap like this always goes wrong when doing mechanics just remember to fight one battle at a time and you will win the war. One last thing if you have Hei with the big cap take it off first or you will break it.