8 3/4 rearend swap in 70 dart

i have a 66 barracuda A body 8.75 rearend, and Im going to swap it in my 70 dart.
what complication or issues will I faceother than drive line shortening and using 8.75 shock mounts and u bolts? will the brake lines in my 70 dart 7 1/4 work?

any info would be great