[cobrashoch]

Johnny - Iron faced aluminum flywheels are pretty much the standard fair for street flywheels. They use iron in various configurations to stop warpage when the wheel is hot from abuse or if you simply just ride the clutch. In any rate the flywheel is most likly not the problem.
Assuming all of the stuff in the replys above all check out o.k. I really think you possibly are going down the same road I visited many, many times.
Got 600lbs of torque? check
Got big ol' tires backside. check
Street long styles will break eyebolts and warp.
Centerforces are a joke.
"Pro" diaprams stick to the floorboards from time to time, and slip as they age.
McCleods slip with big tires too, are more expensive but are mostly o.k. for streeting around. Forget thrashing them hard though.
6 bolt hot rod pressure plates mostly are just expensive and don't really work well.
After fooling around with about 25 or so clutch combos it seems I finally found the "right'' thing to do. It's a bit different, and a lot more expensive to boot though.
It's the pro long style "competition" clutches sold to super stock racers. These long style pressure plates have 12 bolts that circle the perimeter equally spaced and require the matching 12 bolt flywheel. This type of pressure plate just plain will not warp, break eyebolts, vibrate or any of that junk. When using this style of pressure plate, with all else being equal, you can use a slightly smaller clutch disk, together with a slightly lighter clamping weight. About 2800lbs is about right for a 2500 lbs car I would say. Most of these types of pressure plates are also factory rebuildable.
I'm not even going to tell you what I put #39-608 Hayes comp. long style through for 4 years, and lived it did on the street/strip. It was just a 11 incher with a Ram bonded and rivited disk for a big input toploader, and this setup held a set of M&H 1050's in a 3000 lbs car! If you choose to investigate this idea I'd bet even money you will not regret it.
cobrashock