need help to fig out value of a 1972 duster

im looking at a 1972 duster 340...its a very nice car its yellow with the 340 wedge decals...not sure if its a real 340..the guy isnt sure what motors in it or much about it and that kinda has me wondering..i havnt seen it in person yet..just wanna make sure its worth the 4 hour drive to see and maby purchase..need to find out if its a real 340..or what to look for to find out..what do u guys think its worth? say its just a 340 clone at worst whats value on it then? any help id appreciate and be thankful..just dont wanna make a big $$$ mistake..heres the pics any info u could offer would help