As mentioned, unless the Pantera is a late model or has been updated to that level, there is a welded crossmember in the way of removing the oil pan. If so, cut it out and modify it to bolt in.
Once thats done, the pan is drained and removed. Oil will stop dripping in your face after awhile.
The rear main bearing cap is unbolted. Half the seal is in there, to be easily popped out.
The second half is up in the block, and can be tapped out around the crankshaft. To not scratch or mar the crank, use a piece of brass or aluminum- even a wooden stick- to tap it around and out. And as they always say- reassembly is the reverse of the above....
Caveats: '71-72 Clevelands used a 'rope seal' not available anymore, and due to the initial high drag of these things, there's a steel pin in the main cap to prevent the seal from rotating. Tap the pin thru and plug the hole in the cap with silicone- a pin is not needed with a modern neoprene seal.
And if your engine was further modified with a one-piece seal (not stock on any Cleveland), unbolt the ZF & bell housing, slide it back as far as possible, remove the clutch & flywheel, remove the rear main cap and remove the 'fail-safe' one-piece seal. A std two piece seal can then be reinstalled, or if you wish, a one-piece seal can be reinstalled.