Before you tear stuff out that may be OK, check out your clutch: while a friend puts the clutch pedal to the floor, try sticking a feeler gauge thru the bellhousing window, between the disc & flywheel. Most stock Panteras get about 0.030", which is ragged- edge acceptible (0.015" on ea. side). More is better as long as you have some free play. No free play= slippage plus clutch and throwout damage. If you don't have any free play, consider buying a long-throw slave to fix this. FYI, a double-disc clutch will require twice the .030" disengagement distance, or massive clutch drag will quickly wear out the ZF's synchros. It's not the horses you have, its the torque that drives guys to big clutches. A 10-1/2" Mustang clutch should hold 450 351C horses (Panteras came stock with an 11"). A diaphragm type clutch will make pressing the pedal down much easier while still holding the power. Mid-'70s 454 'vettes came stock with a double-disc diaphragm-type clutch. Finally, if ANY trace of oil is seen dripping from the bellhousing, slippage is coming from this, not from any design problems. An aluminum flywheel allows the engine to spin up faster but becomes a real pain in street driving if it's too light. And the thicker crank flange area on alloy flywheels means you get to readjust all the clutch settings, since the clutch is moved backward relative to the bell housing.
