1970 Road Runner

Thanks for all the replies! I can't go see the car in person but have bought many cars like this but never a Road Runner. What are the definite things to ask the seller regarding the authenticity of this car? Is the 69 440 short block a negative? Were all 440 engines in these cars short blocks?
The short block is the engine minus the heads and manifolds. When they say 1969 short block it means the engine is a 1969 not a 1970. If this car is a six pack it would have come from the factory with a special engine which is no longer with the car. This will lower the value perhaps 10 to 15 percent (my opinion). You should ask the seller if they have the original engine from the car and a clear title.
Most importantly you should get the serial number of the car to verify it is a six pack car. The easiest to see are on the dash, the drivers door, the data plate under the hood, the radiator support, and on the left side of the transmission. Have them send you good pictures of the numbers.