I know tons of guys here have done the swap from a 7 1/4 to 8 1/4 in an A body.

The original 7 1/4 is long gone. When we got the 8 1/4 swapped in, we found it's e-brake cables are to short - driver's side a couple of inches; passenger side a couple of feet. What's the fix? Cables from a boneyard 7 1/4? Are they a straight swap? The car in question is a '70 Duster.