The quick overview of technical enhancements is posted on the Performance Unlimited site. This is also home of SCOF (Superformance Owners Forum).
http://performanceunlimited.com/supe.../features.html
Conversion requires new motor mounts and header kit and possibly the bigger spline Tremec. Small block Cobras are still fast cars. If you are interested in a BB, it might be better just to get one instead of doing the conversion.