So you are using a LCV block and using LE9 crank rods and pistons or keeping the stroke of the LCV?
We have used the LDK blocks with the bore changed for the 2.4L and the LEA blocks with some machine work needed to get it all to work correctly in the Slingshot. The bore and stroke are still maintained the same as the stock LE5/LE9 engine (technically the bore is changed slightly with the custom oversized pistons we use by .5mm, but basically the same bore). It is a little confusing though since the LDK and LEA are technically a 2nd gen block based on the Wiki page, however other vendors and customers have always called these block a "3rd gen" block, not sure how that started, but in the Solstice/Sky/Cobalt world that is how these blocks are referenced. There was a change to the 2nd gen blocks with the introduction of the LDK, LEA and LAF block from Opel that included the upgrades to the block listed above, so really these blocks would be more of a gen 2.5 block, but like I said, other vendors call it a gen 3 block. The true 3rd gen blocks didn't start until the LTG and LCV, but those blocks are completely different than the 1st and 2nd gen Ecotec blocks and are not interchangeble into the Slingshot since they switched the sides for the intake and exhaust on those engines along with a lot of other changes.
Hope that helps,
Dave