Big Block or Small Block in my 70 Duster

just my two cents but id stick with the 340 if i was going to do a good amount of street driving. im building mine with a 360 because its what i got. when i do build a BB A body it will be an all out balls to the wall racing motor lol. something like a supercharged 528. On a side note the fastest car i owned i picked up from a legally blind guy(so he never got to drive it) that got it as a present from his nephew. it was a 67 valiant with a dyno blueprinted 360 with 625HP!! (on the motor) i had all the paper work drove it daily raped my wallet on gas. That car was the only car that scared me if i put my foot into it. would break the tires easy at 70mph and i only paid 1200 cash because he had it for 12 years and only ran the motor in his driveway. just wanted it gone and some one to love it.