1st off welcome to a great place to learn and get information about hot rodding. Let me start by saying that the words budget and blowers have nothing in common. You can get your 400/500 horse a lot cheaper without the blower set up. What are the #s off the block you have? Your best bet is to after getting a true positive I.D. off the block, run it down to a reputable machine shop for a cleaning and inspection for any flaws and cracks. Then get it machined and prepped for a 500 horse build. The only usable component from the motor will be the block and main caps, only if they are 4 bolts. I would use a 6" rod 383 rotating assymbly with some Brodix track one 2.08 aluminum heads. Along with a Brodix Intake and a Holley HP carb and a complete MSD ignition system. Cam will be determined by how much street and strip time it will be used for, and cars weight, rear gear, and tranny used.