Have any of you seen anything on the web about turbocharging a Cadillac 4.9L? I mean is it even possible (I'm not sure it'll fit) to make a custom setup, or am I gonna have to find out on my own?

Yes there is a Turbo Cadillac Engine. I believe it is a 4.6 liter quad turbo or twin trubo. Same block as the 4.9 as they all are from about 1985.

About 1000 horse power. But it's the Cadillac Indy Car.

in albquerque new mexico find the # for flash auto they bought caddillac motorsports they can build you a caddillac motor just about any way you want it depends on how much money you have also try looking for caddillac motorsports on the net