yep.... it is for the fitting of an OHC engine.
The OHC engines were fitted as a complete assembly with the subframe, and either in production or when working on it the car is lifted off and lowered down onto the subframe and engine as a whole.. That 'wobble' is so the front panel clears the cam pulley bolt as you lower the body down onto the engine and subframe assembly.
Or so I was told many many years ago by the most knowledgeable vauxhall man I knew... who has been known to take the *Bleep* slightly from time to time so maybe he was winding me up, but I had the story corroborated by the guy who trained me so maybe it was true...I dunno....but ... it
does just clear the pulley bolt when lowering the body down onto the engine and subframe so if it is true, or just an old wives(vauxhall mechanic) tale, either way it works