If you're using the sb chevy, then get a flywheel drilled for 12" clutch. Run the clutch out of a 6.2 diesel. Mine had a hydraulic throwout bearing, but I think you can interchange the throwout bearing, don't know. You'd have to ask the parts guys. The 12" clutch, I got a RAM for towing from Summit. With a 6500 lb truck and a healthy 400 I couldn't get it to slip pulling a 30' cattle trailer fully loaded. On the other hand the 11" clutch in my 400 ford using Autozone stuff sucked. I finally threw the disc away and bought a top of the line Big-A HD disk the last time. It held up a little better but the difference in holding between a 12" and the 11" was night and day.
I've had decent luck with the Borg-Warners from Kragen???or Pep-Boys. Nothings going to hold up to slipping the crap out of it, but the more organic it is, the easier it is on the flywheel. A long-life semi-metallic type will get grabby when they get hot, and they wear the flywheel a lot more. The metal puck type are totally unsuitable for slippage. They are like and electric switch, on or off, no inbetween.
