1964 El Camino Exhaust

This is a 1964 El Camino with a 1970 350 (pulled out of my nova) in it. The exhaust manifold is fine but the pipes coming off of it that were originally there, have been cut, and no longer extend even halfway beyond the cab. This is causing mixture issues and overheating, along with several flat spots in the motor. Also, it friggin reeks in the cab of exhaust...that can't be good for you. Now I want to extend the existing dual pipes to add material.

Here is the layout. Exactly in the middle of the cab (measuring from the front of the cab to the back) about a foot apart from each other on the the underside are the two chopped off, existing exhaust tubes. At this cutt off point there is a step down from 2 3/4 inches in diameter to 2 1/2 to 2 1/4 inches, roughly:

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Now the original intention was to get rid of this "nipple" to open up the diameter, and then route the pipes out the side and along the bottom of the body. I was also told I could run them out of the underside of the front wheel well and down the side as well. Going straight out the back seemed like too much work to try to get the pipes over the rear axel cheaply and efficiently.

So the question is Can I route the existing pipes out the sides, or do I need headers, a different manifold, etc. which would be the best way to route them without changing too much, but maintaining a very LOOOOONG wide side pipe down the length of the wheelbase, on the undercarriage runner. (sorry if terminology is off, I just put the stuff together I don't know the names of every single little piece but I am trying to learn, so tell me what it's called)

Thanks for the help!

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