need some roof replacement techniques

So i'm thinking about entering the unknown with some help from some buddies, one is a general fabricator. My 72 dart swingers roof is shot to all hell and i don't want to give up on this project since I already have a lot of time invested in it. I'm looking for some tips and tricks from the mopar gurus on this site. any advice would help, such as how to keep the roof in place well welding ect. I've found a complete donor roof and want to jump in. Help!