Lemme ask one more question here concerning the heads with mechanical valve springs. My buddy at work has a 10.50s N/A 347S notchback. He has the AFR 205 heads and he has 10.9:1 CR. I asked him about the springs and he said he just converted his motor to Mechanical Roller instead of hydraulic roller, which most of us know can handle more RPM than hydraulic. My question is, since im planning on ordering the whole valvetrain soon (including the retro-fit hydraulic roller lifter kit to make my '75 351W block a roller) should i just step it up to a mechanical roller setup instead? From what i understand, the reason that you have to get retro-fit lifters to run a standard roller cam is b/c the lifter bores are to short in a flat tappet block, and the roller blocks have longer bores?? right? The guy at work said that the Mechanical roller lifters are shorter than the hydraulic roller......soooo.....could i just run a mechanical roller setup without doing a "roller conversion"?? I think i may go out of my mind soon! Just so many dam options! Can i even do this with my block, or just stick to the hydraulic roller