LT1 can be ls1's daddys just ask Joe Overton, or pick up GM high tech and see the cover! Weak points for ls1 heads(flow restriction) and opti. Now you can get a coil conversion(thank F'ing God) and there are some porters than can do wonders with LT1 heads. Building a big NAWWWWWWZ motor or FI I would feel more comfortable with the lt1 , the ls1 ghey boys go lq4 (no names mentioned,LOL) block due to these concerns. In stock for the ls1 is like the lt4 and will whoop an lt1. Modded in depends on how fat that wallet is.