budget street motor 360 or 383 for 71 duster

AJ is spot on and 400 hp is about all the op will achieve with his budget. Realistically he is looking at about 8 -10 grand in motor and chassis work to reach his goal and work on the street.
8 to 10 grand? I only had Close to 6500 in my 440 in my 73 dart. But I will say I bought the short block used. I payed 2800 for the 440 short block and around 3500 for the Indy ez heads. The 440 was built to run on 93 pump gas and my 73 dart weighed 3520 with me in it. The car ran 10.60 at 126 with the wrong torque converter. Just trying to say that you can build something pretty cheap if you can find deals on parts.