Definitely remove the spray arm and racks, especially if you can't keep the machine upright.  By all means do so if you can, but it's not critical.  I recently rescued a 12 and moved it on its back with no ill effects.    If the machine has been in use, you may get some water dribbling out of the pump housing; I always move things like this on an old blanket just to soak up any such spills.

Be very careful not to let anything rub or knock against the pump chamber - they are fragile bakelite and replacements are near to impossible to find.      Please post some pictures when you get it home!