Interesting topic this......
Having seen - and nearly caught by - people turning classic Saabs into things they never were I'm probably a bit biased but here goes - I agree with what others above have said - if some one wants a particular type of vehicle - say a "Pink Panther" from the Reg'ts days in Oman - and there are none available either because they've all been destroyed, are in museums or what have you then taking a similar spec vehicle and converting it is a reasonable thing to do as long as it is declared as such up front if being sold on or entered into a competion of some sort.
After all - this is only what the military did themselves. However - if the vehicles do exist - as Panthers do - then converting a LWB into a replica should not be countenanced. Period. For those events which involve judging standards of vehicles I believe that replica's should start with a certain number of points deducted for the simple reason they ARE replica's - it's a hell of a lot harder to get a vehicle thats seen active service into show condition than it is to take a vehicle thats spent most of it's life either in storage or in barracks.
As regards Cara and Micks Clubmobile conversion - I personally reckon this is a good thing they are doing as none exist now, apart from theirs, and to have one to show future generations what their grandparents went through is a big plus in my books - too many people are trying to "rewrite" history these days so physical evidence of the equipment and conditions in use can only ever be a good thing.
Well - thats my tuppence worth - hope it hasn't upset too many people!!!