all my originally 318 70 darts came with 10 inch drums all the way around. Never heard of an A-body with V8 and 9 inch drums - always thought they were a /6 only thing...
These days with the car in front of you sporting 4 wheel discs, you better be real conservative about how you drive in traffic, or upgrade the brakes. If the car in front of you locks 'em up you better be able to stop as fast as they can or have lots of room between you...