shevy, 280 hp from a 283 is, in my opinion, very ambitious. At the pinnacle of their development, 283's made 270 hp with 2-4 bbls and 283 hp with Rochester fuel injection. This was done with 11.0:1 SCR and a very large cam.

Don't worry about hp right now. Just get the pistons in your hands, take the block and pistons to the machine shop, have the block bored and honed, rods resized and piston hung on rods. Then put rod/piston assemblies (without rings) into cylinders 1,2,7 and 8. Using a dial indicator to find TDC and a depth gauge to check deck, find out what the deck height is on each corner. Gauge each piston at the 3 O'clock position, not at noon or 6 PM as you're standing at the side of the block. Write down each measurement, then publish all the info on here and let all us gearheads get our heads together as to the best way to proceed at that point.

IF YOU HAVE NOT PURCHASED THE CAM YET, DO NOT. IT SHOULD BE THE LAST THING YOU BUY FOR THE MOTOR AND WILL SET YOUR DCR.