I have a 94 Z28, I think it has a rod knock. I'm trynna figure out if I should rebuild it with a 383 stroker. I need to know what length rods I need. what is the compression limit for 93 octane? should I juse use regular pistons with it? most of the engine is new, except for the bottom end. I also want to know how I can tune the computer for a 160 spedometer, the car did not come with z rated tires, and it bothers me that a fast car would only have a spedometer that tops out at 115.