Memphis,
It would be best to get in touch with a owners club, and maybe start with somewhere like the Sporting Escort club.
While it is nice to get a original Mexico it will always be more expensive to insure and buy than a "standard" Mk1 or 2 that has been upgraded to a similar spec, so Per's suggestion of a "Sport" is a good idea, also you could consider a 1300E Mk1 .
Of course if you can get a RS car then it is a good investment as it should never really lose any of it's value if properly kept, and may even go up in value.
The club should also be able to point you in the direction of an approved insurer offering a club scheme. You may have to agree to garage the car or restrict your mileage for the year, but it can save a lot of money, and the car will be covered for a proper value.
As a last word if you are looking at these cars take along a friend who can give impartial advice and who is knowledgeable about the car you are looking for, there are a lot of fakes out there, and an awful lot of badly bodged rubbish, some of which shouldn't be on the road anymore, it is all too easy to get carried away and end up with a hound.
If you want any advise on what to look out for when viewing or buying one of these cars feel free to ask.
good luck with your search.
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