Tranny pan gaskit

I am wotking on a 727 witch i must of had my stupid light one last winter.thats when i should of replaced the gasket well now it is leaking.So any tips on reinstalling the gasket would help,you know ten brains are better than one . if the pan is a little out how should I address that issue as far as getting it flat.i did however change the front pump seal.Thankssss all.