HELP! Need 8 3/4 Rear end for 70' Duster

You can use a B-body rear without cutting it. Just replace the spring perches and get wheels with the correct offset. The rear track on an A-body is 55" and 59" on a B-body. I have a friend with a '74 Dart Sport with the spring relocation kit, B-body rear and he runs 29550R15 tires tucked under the fenders no body mods.