The truck idle pulley runs up high where the throttle body goes when using the LS3 or L76 intake. That is why when you go with stock parts you have to match the intake to the accessory being used on the motor. The guy in the picture below was slick when setting up his DBW LS3 or L76 intake on his truck engine. He fabricated a bracket to relocate the idler pulley. I prefer to use stock pulleys whenever possible because they have a much higher track record than aftermarket bling bling.
Also, notice the throttle body in this pic. This would be the correct four bolt mount LS2, LS3, or L76 style tb that mates up to it. Your throttle body should also be 90 mm and have a four bolt mount, but it should be shaped different than this one. 2007 was an odd year and there could be a couple of different things going on. However, I would suspect you have a SIX pin wire harness plug on your tb.
On the older models you had to get a conversion box to plug into then go from there to your t/b to do this swap. The guy in this photo has one of those as noted. You should not need that on yours. However, it is possible your t/b will mount to the LS intake - but I'm still trying to confirm that.
Picture below is of the older style ECM with TAC module type harness that requires a conversion box to attach the correct t/b to this intake the TRP X-Link 2.1
