I have a 1984 GT350 that I put a 351W into with a C4 transmission. My C4 is a case fill with a 157 tooth 28 oz imbalance flex plate. When I engage the starter it makes an awful grinding noise and I am unsure if the engine is turning over fast enough to start. I loosened the torque converter nuts and there is play in the converter it is not bound up and the noise does not go away with the nuts loose or off. I checked run out with a dial indicator and it is only 10-15 thousands of an inch out. I have tried multiple starters. 2 of them were brand new. I have pulled the transmission and inspected the block spacer plate for any signs of scraping or rubbing and there are none. There is no sign of contact anywhere on any parts other that the gold finish is worn off of my new flex plate where the starter engages the teeth. Also the engine turns over fine by hand with absolutely no noise or resistance. Any assistance would be appreciated. Thanks! I have a video of my issue but it will not upload so if any one would like to see that let me know how I can send it to you. Thanks!