check out the installations section in www.hotrodlane.cc . They have motor mounts and everything you'll need to do a conversion into the Caprice. They have the buildup for a couple of Caprice cars demo'd there.

For facts and figures about the LSx engines, get Wil Hanzel's book on building performance LS1 engines. There is a lot of good reading there, highly detailed. HPBooks also has a nice book call Chevy LS1/LS6 Performance. You can get both books online for about $30 total if you shop around.