The numbers and letters on my guitar are confusing and do not fit in with any i have been looking at. The only thing i have found is that RM may refer to Ryoji Matsuoka who stamped RM on high end Aria's in the 1960/70's.i.e. his initials.
The guitar has the Suzuki Guitar Suzuki Violin Co Ltd Nagasoya Japan. The heel block inside has what i think is "700327".
The label ,after the word No. has "1663" stamped and the bottom of the label is also stamped "RM9749"