Help convince me to go BB in my Duster?

74 SE? is that the application for the booster? What is it. Mopar used a lot of diff parts. It would help me track it down. I gotta keep m ps pdb and ac. Was gonna do a 451 for better fit, but decided to keep it simple.May have to do a gearvendors overdrive cause I want to drive it a lot. Was easier to do at .99 cents a gallon as to 2.80.