The paperwork that you received is enough to document the fact that your rifle.......by serial number........ is an original & genuine NM Garand. Congrats guy, you got lucky.
As far as being able to tell a real from a humped one......... be advised that there seem to be a bunch of very good fake M1 NM rifles, M1D rifles coming from the Gulf coast area of the USA........... so good that they'll fool the experts & they cannot be found in any DCM/CMP files............ that's because they were built from Blue Sky & Arlington Ord. imported Garand receivers.......... using original USGI NM barrels & parts., the same on the M1D's.............another scary fact is that some of the guys are talking about faked DCM & CMP papers......... I haven't seen any yet...... but that is scary..............
be safe, enjoy life, journey well
da gimp
OFC, Mo. Chapter