One option for you for this combo is to have the LS3 built with a 24x crank and use a 1x cam sensor and use the wiring harness and computer from your LS6. We purchased a 418 LS3 short block from Texas Speed last fall to replace a blown up LS1. We had it built with the 24x crank so we could re-use the wiring and ECM from the LS1. The combo uses a built 4L60E behind it.



There are lots of options available to you and any of the vendors that have already responded can help you sort out exactly what you want.