71 mach 1

hi im looking to buy a 1971 mach 1 mustang is there any way to be sure tthis is what im getting

http://www.mustangmonthly.com/featuredvehicles/5771/

Here is a guy's Mach 1 that is like 80% original. It should give you some information about what you're looking at.

VIN number, check it online

Check numbers those 351's are around 18,000 now I believe