I have posted the except of AC 45.2E that I have used to try to convince FSDO Airworthiness Inspectors the PA-18-135 in front of you is identical to a PA-18-150, and it can be easily proven, with 100% certainty, using FAA approved and accepted data, primarily TC1A2 and the PA-18 Parts Manual, without success.
Changing Identification Plate Information
You may change the identification data required by § 45.13(a) only when such change comply with specific FAA-approved or -accepted data (for example, design data,maintenance procedures, and rebuilding or alteration procedures contained in manufacturers’ manuals, letters, bulletins).
Note: When an aircraft has been modified to conform to another model of the same make, a new identification plate is required to be attached as close as physically possible to the original identification plate. The original identification plate is not to be removed or altered in any manner.