If I remember correctly The 300 is the lighter ,Cheaper version of the Chevelle. With a stock 327 the car should have easly turned in the mid to high 14s. Not trying to hurt your feelings,but you need help. I would not spend one more dime at this point. You are so far out in left field,that I would find someone, even if I had pay them $100 to go to track with me for the day to evaluate what I had and then he could make recomendations. Who knows? he might have You running 2 to 3 seconds faster in a few minutes.Make sure You select someone with a proven track record so You dont waste Your money. None of us are there with You and you're so far off its very difficult for anyone to say what the problem is. It could be something simple.I hope so!