I find the three biggest problems areas follows (in order) I've put on thousands of cork oil pan gaskets over the years....they work just fine.
1) previously overtightened, and then subsequently not repaired dimpled bolt holes
2)aftermarket cough dorman/spectra cough pan that has garbage stamped corners
3)gasket was lathered in RTV so much that it turned it into a slippery linguini noodle, and then whaled on so tight that it just slides right out.
Remember, if it leaks from a few holes after you are done, clean the area up realllllllly good with brake clean, hook a shop vac up to the oil fill, and suck a little RTV into the hole. Be gentle. Fixing **** is usually more about precision than it is about brute force.
Weater strip cement the cork to the block and timing cover, a small dab of RTV on each corner, make sure that the end gaskets fully seat in the registers(especially the corners), make sure the pan surface is flat, VERY thin RTV coating on the cork surface, then care fully and evenly tighten it up....