I`m sure the M & P catalogue used to do universal motocross bodywork for dirt bikes with hard to get or damaged plastics....dealers or breakers are your port of call if you want o.e...
if you want original you will struggle if you want to modify pattern ,no problem any decent mx shop should be able to help .http://www.davidsilverspares.co.uk/ are worth a call they don't tend to do mx stuff but may point you in the right direction .