Stretch
Hey! There’s no easy button for a body like this!
Make sure the car frame is perfictly level when you weld that cage in. Level and ridged = fast! Before you get too far into building that, look into a book called Street stock chassis technology. That book is old but it's full of chassis building info. It talks about all kinds of stuff like "roll centers" Unsprung weight" "spring rates" and there effects on handling. Hell P.M. me your address. You can have my copy. I doubt I'll ever need it again.