Good suggestion might work, thanks. The support currently sits between two of the carburettor inlets and is bent outwards to clear the carbs well with no filters. I have bought 4 filters, similar to the left hand one in the image, and they are not far off fitting - three fit perfectly. The Ramair foam might well work but I think would deform against the support, but would probably allow the bonnet to close, but I suspect would eventually dislodge as the bonnet is opened and closed. I see that they do flat foam filters in pairs and they may work without adjusting the bonnet support, I am just not sure about forking out another £70 odd, to find that don't quite do the job and, to be fair the others look better!
What I should do I suppose is take that support off and see how much extension is available, maybe it will bend out more. It would be nice though to get another one, in case, and also to bend while the other one is no to make measurement simpler.