Hello Racco,
The manifolds are the critical factor in a street version, changing the roll bar, hood, scoop and filling in the outlet for the sidepipes on the fibreglass are easy to do but, will require a repaint of the entire body to look right. The old iron manifolds are very restrictive so a new design tube header is the solution.
I have researched this for the Shelby round tube frame but, not familiar with the Contemporary chassis. The issue is how you run the headers down and then back under the car, placement of the mufflers, welded tabs to secure everything tight and heat shielding under the floor etc.
The SPF street roadster comes with all of this sorted out but, only for the small block windsor motor, when you order the shelby version you get sidepipes and must fabricate a field solution (SAI Direct Words), for the conversion you are asking about there are few solutions or you need to fabricate your own unless you have a local craftsman that can undertake that aspect of the project.
Here is link to a series of picture of a David Wager car one pic is of the passenger side but the driver side is much more complicated with the pedal box etc. and a narrow path for the exhaust. This is an Aluminum Kirkham car, David also provides an Aluminum slab side version.
http://www.dynamicautowest.net/detai...r-3315063.html
Rod has given you the Mike Mulcahy site and they look good for $3K, Tim Gunning also sells them at Sagebrush roadsters for less and they look like similar quality. Call Tim directly, they do not show them on the web site.
http://www.sagebrushroadsters.com/
Tony R.