That is a loaded question and hard to answer without more facts. 340 is a great motor and orange paint is awsome... add that to a 1970 Challenger and it has the recipe to a great car. As far as price, that is always speculative. But these combinations have proved attractive and profitable on a Challenger. Give us the facts on the car and the VIN and what shape this whole package is in. Then we might be able to help. You might find one that is in similar condition on E-Bay Motors and compare the purchase price as an idea.