For US models - K5 ('72) tanks had a chrome strip along the bottom, black headlight shells (in the larger 7" format), a seat with pleating in a checkerboard style (side hinges), and chrome fork ears - while K4 had painted headlights/fork ears, a seat with pleating like yours shows (rear hinge) and no chrome strip on the bottom of the tank.
Both K4 and K5 had those air cleaner cover emblems.
If it's a US model, the VIN should tell you the exact model you have.
Looks to me like a K4 in "Valley Green Metallic" with a replaced headlight shell (the smaller type). Serial number should be CB450-4100001 to CB450-4999999.
If the serial number starts with 5, it's a K5 with a replaced tank/fork ears.
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