Rear tinware query ‘74 bug

This is driving me nuts. ‘74 Beetle 1600 twin port and will have twin Weber 34 ICT’s and J tubes so I need to change the rear tinware over the exhaust for the type with no holes. It has the “wider” breast plate.

Problem is I can’t find anywhere the right shape rear tinware, they all seem to be moulded for the narrow breast plate?

This is the one I bought but it just doesn’t fit:



The breast plate:


And comparison with the one that came off which also wasn’t a sound fit:



Question then, I am wasting my time trying to get the right rear tin? Any issue if I switch the breast plate for the narrower one which should fit the replacement rear tin I already have?

cheers
Lee