It was just an experimental design and was cancelled in favor of the B-1 Lancer which was better because it had swing wings.
The six-pack engines on the B-70 had big overheating problems that were unsolved.
Also if one was damaged it could affect the five others with a fire.
The B-1 has jet engines that are widely separated for safety reasons!
When I was there I was in Hangar 18 and all I saw was vintage aircraft like the A-12 Blackbird and a Flying Pancake!



)