Yeah, it is late. The cage I am planning is going to be a lot like the one in Stevo's car, but the a-pillars will go through the dash, and the door bars will be a bit different.
Total Control Products is building a pretty wild track car
http://www.totalcontrolproducts.com/...ecar/main.html might be good place to look in terms of a project headed in that direction.
Maier apparently has some stuff for the early 'stangs as well.
http://www.maierracing.com/index.html
I dunno about their early stuff, but their late model stang stuff is pretty widely used by the guys racing in NASA.