Ignition Switch Cover 1972 Interstate 750 Commando

I need a little help with the difficulty I am having sourcing the pliable cover for my ignition switch (see attached photo).  When I decided to replace the entire ignition switch (with key and tumble lock) on my one owner fifty year young 750 Commando,  I also ordered the pliable cover as the original was quite stiff and developing some brittleness. That part shows up in the Norton Commando part book.  When I ordered it from Baxter Cycle ( a GREAT Norton parts company) I received a two piece ignition cover instead of the one piece original.  Logan, the parts gentleman at Baxter, said I did use the correct part number for the cover but the design had changed to the two piece variant with the original piece part number.

Simply put, I could tell by inspection that the two piece cover would not fit,  the inside diameter near the front  by the key entry  was too large and there is no place available to locate the rear piece. The original has no rear piece.  I felt this might be an ignition cover for the police version of the bike or perhaps a previous Norton model like an Atlas. 

Is it possible that the cover should be loosely fitted and then shrunk with heated air to fit?

Alternatively, does our club spares have a replacement for the original single piece variant?

I seems to me that the only way to remove the old cover is to cut it off.

Any thoughts or inputs are welcome.  

John Morrissey in the Colonies

NOC402598