There is a guy on eBay, magic30pink from stoke who makes them, they don't fit bad at all, I put one on my replica to replace the mc rallying one that was on there, he even glasses in side bolts so you can bolt them to the original mounts below the wing, they are cheap as well the only thing I can bring them down on is I thought the fibreglass was a little thin so you may need to layer a little more matting inside.

This guy

http://m.ebay.co.uk/itm/ford-escort-cosworth-bonnet-vents-/202037684053?hash=item2f0a626755%3Ag%3AlZ0AAOSwDN1 UUOd1&_trkparms=pageci%253Adffda480-8d63-11e7-aed8-74dbd180741a%257Cparentrq%253A326d45d515e0a866454a 35f9fffc6c9b%257Ciid%253A2

He hasn't got one listed on eBay at the minute but im sure drop him a message