69 or 70…….2 or 4??????

I have a 69 4 door dart (273 auto, 2nd owner, real solid, runs good). I may be trading for a 70 2 door (/6 auto, newer paint, runs). My question is how different is the values on these cars? I know the 2 door is more desireable, but in similar condition is it a huge difference in value? The 4 door is all stock in good shape. The 2 door has been painted different color and will have a v8 installed. I need to decide how much boot would be fair on the deal as well as long term value.
Thanks,
Andy
Author: admin