I just recently put a high dollar ( to me anyway) supercharged 355 in my 68 Malibu. It has all of the stock pulleys that the original 307 with PS and AC came with. Every time I twist the motor over 6000 rpm it throws off the belts. Yesterday it took out the blower belt and trashed the idler in the process, a $240 expense not to mention the embarrasement and headache! I know deep groove alternator pulleys are available but what about water pump, power steering pump,a/c compressor and crankshaft pulleys? I've used new belts and everything looks in alignment but this is still happening. Any ideas? Thanks, Bob