Like others have said...Keep the original frame and upgrade it with modern suspension. Pying someone for the fab work won't be cheat but quicker and better than swaping the frame. I have about $950 in my chassis not including wheels and tires. Did all the fab my self. It has a 75 camaro subframe and a custome made 4 link. There are a couple pictures of the chassis here
http://rides.webshots.com/album/578128249XNyAVS