I like this style also and plan on doing a version for my car. There are some good photos on the DSE site that show how the doublers are done on the inside.
http://www.detroitspeed.com/Projects...dee1969184.jpg
Also I really like the one the Dutchboys did.
http://i119.photobucket.com/albums/o...psg7rgpzwe.jpg
https://lateral-g.net/forums/atta...1&d=1435562511