I am in the middle of doing the relocation for my 66 barracuda and was wondering if anything has to be done with the shocks?  Also does the driveshaft have to be shortened to be swapped from the 7 1/4 - 8 3/4" rear end?

I don't believe you need to do anything with the shocks, but the driveshaft will have to be shortened. I had to have mine shortened when swapped from 7 1/4 to 8 3/4 in my 64 Barracuda.

The shocks will be OK at normal ride height. If you get the car real low the shocks could bottom-out in their travel.

As for the driveshaft, yes, it will have to be shortened by appx. 2 inches.
Get the new rear end installed then measure. Be sure you have the rear springs / rearend at normal ride height (not hanging) when you take the measurment.
DD