rear disc brakes vs rear drums

Well just my 2 cents, don't mean to step on anyone's toes.
Rear drums should work fine but....the 11" drums are HEAVY. Can't remember the exact weight so I'm not gonna quote it but I believe it's around 30 pounds each. Not only is it just the unsprung weight but everytime you accelerate or decelerate you are using energy to get those things rotating. Unless you are racing down Mt. Washington or Pikes Peak, I think it's overkill on an a-body. That's why changing over to lightweight frontrunner tires/wheels on a drag car reduces the ET. I remember High Performance Mopar magazine did a simple A-B test and they were good for .15 seconds(?)

Personally I went with manual 73-76 discs on the front and BBP 10 x 2-1/2" drums on the back on my 68 cuda. Standard 10 drums on a 67-69 were 1-3/4" wide so I only added slightly more weight. Also changed to a newer 1-1/32" dia aluminum MC with an adjustable proportioning valve and eliminated the brake safety valve/tee to simplify things. KISS is good and less joints to leak or cause problems. So I tell people I pretty much have B-body brakes on an A-body and they work well for me. Not only are the brakes bigger but I'm hauling 400-500 lbs less weight too.