About 14 K for a complete setup. Special harness, ECM, Tranny, and related parts including custom headers, radiator, etc.
The first confirmed Hemi powered Cobra was built by a gentlemen called "Wing King", now of Viper fame, in the early 70's. If I remember right it was written up in "Auto Week" at the time. Quite the story.
DV...spread the frame-lower the motor, we "think" it will fit!
But,...the Gen. III Viper motor is still faster AND lighter!