Swap from 7.25 to 8.75 advice

It was a 318 car, his valiant is a 318 car. Both are 2 door cars, 904 transmissions. But we did get the driveline as well. It came as a complete full drivetrain from radiator to rearend. It was a coastal range car, so it is completely rotted from the middle of the car to the bottom of the quarters. Lots of good parts on it. Pulled the numbers matching engine and transmission already. As well as the driveline and rearend today. Pulling k frame and front suspension next. Then glass, dash, seatbelts, etc. Is the dart a longer wheelbase? I know dart and dusters differ.