Big Block Dart Decision

Made a deal with a feller yesterday. Guy has a 68 Dart with a 383 / 727 / 8 3/4". He wants to remove the motor and put it in his Road Runner, remove and store transmission and rear end. After that the car is mine . The car is not 100% missing interior and trim . Inner fenders are removed for headers. rust on rear 1/4s and no title.
Right now I am in the process of building another 67 FB. Should I go with a small block I already have or use the Dart K frame with a 68 383 ?
I have too many projects already to try and rework the Dart. Is there any value on the Dart with me keeping the K frame and selling the body? Or should sell K frame with the body anf put the small block in my Cuda?
What does these cars go for?