Using the clamshell mounts on an ICT Billet adapter puts the engine in the same place, or 5/8" forward if you need to not hit the web on an aluminum block. I used Holley mid mount adapters (Corvette/Pontiac G8) for accessory mounts. Everything clears, and it looks almost stock. Oil pan is a CTS V, extends about 1 inch below crossmember and clears everything else. I have a 6L80E trans. Using the original G Force mount from 200-4R I had to fab a 1.4" 4" X 6" plate to mount to the top (Original mounting holes for 200-4R)Th 6L80E is about 3" 3" forward of 200-4R including 5/8" forward on engine mounts. Fabricated a 1" Trans mount (Rubber) and bolted to the 6L80E mount holes. Have between 3/4" an 1" clearance over the top of trans. I am using the G8 6L80E with the three bolt flange output. Had to have new driveshaft built to accommodate a forward slip joint and adapter to the3 bolt flange. Headers are a problem depending on type used. I run twin cats and fabricated a custom 2.5" exhaust using Pypes basic system, + resonators and Pypes street mufflers. Somewhat of am improvement from the 305. 180 HP, 11 MPGH with Fitech FI to LS3 400+ HP, 26 MPG min on road. Change rear gears from 2.56 to 3.08.