If you have the original you are better off to take it to a local friction supply shop. Most cities have at least one. They will disassemble the cover, clean it, surface the pressure ring, check, replace and set plate pressure and replace any parts that need it. If you have a handle on your tune up, you can have them change the plate pressure for you. If not, have them keep it at OE specs.
That is prob all your best bet. As I have written in other places, the diaphram pressure plate is much less expensive to build so the manufacturers are dropping other covers. Sad but true. And then nifty marketing makes the public cry for cheap junk.
