That is always a problem when you add mods that have world generation. Unless you have traveled in your world a lot and I mean a lot. Just generate new areas through exploring beyond what you have already explored and you will find the ores in the world as the new chunks are generated. You could use the nether for fast travel. If you have explored a lot or do not want to travel to generate new chunks then you could always use mystcraft to create worlds. Or use a program to delete the chunks surrounding your base to where they spawn as new chunks. Obviously if you are going to do that BACKUP your save and configs. I will not be held responsible if your 'new' regenerated chunks cause errors or you accidentally delete part of your base or what you wanted to keep with you having no backup.