I noticed that you at one point mentioned re-sale. The engine isnt always what decides the price of the re-sale. You are worried that replacing the original parts with the reproduction parts, this should not greatly effect the price neither. You will be hard pressed to find a completely original mustang that is still in factory or "restored" condition, yes they are out there, but not very many of them. I just bought a 68 for 500 bucks and it hasnt been run in probably 30 yrs, mine also came with the straight 6 but i am replacing it with a 289 because its locked up and not any good. Well, whatever you decide to do since you now have the car, good luck to you and keep us all updated.
