If you go efi, I wouldn't get rid of your donor car until the good one is running well. I've done four, and each had its own set of problems. You may need to change every harness in the car, including under the dash, the dash, etc.
For the rear, just change over to an 8.8 four lug, which I have stayed with on all conversions, and had no problems. Its a major undertaking and cant be done quickly before you set it all up. Good luck.