Header install 69 Dart

Well not like I expected this to be a cream puff but I crawled under the Dart this morning in an attempt to find the engine numbers and found the driver side header tubes smashed falter than day old beer, so a couple of newbie A body questions for you guys. A. how hard are they to install I am guessing they need to go in through the bottom, my one saving grace is I have pretty much everything already removed, P/S pump and hoses and all of the other accessories and brackets

B. Can I solve or reduce the chance of this happening again by cranking the torsion bars to raise the front end up some ( one thing you never see on a Chevy which is making me more of a MOPAR guy)

C. Would it be a better idea to installation and clearance wise just to find a pair of stock exhaust
manifolds and call it done. While I am down there I may as well put in a new exhaust system don't have to tell any of you guys what its like working with rusty old exhaust and while I'm there a nice set of glass packs might be the ticket.

Once again thanks for all your help, you guys rock