Just gotta ask- - - -is there a reason for removing a bunch of rivets? Unless you've got some sort of assembly jig to hold the pieces in alignment as you reassemble it, the frame isn't going to be anywhere near straight and/or true when you're done.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!