Well, if its a DD I'd say go with a 22x duration with up to 580 or so lift on a 114 LSA, something like this:
http://www.texas-speed.com/shop/item...d=166&catid=44
And for heads either ported and milled LS6 or just ported 5.3 (depending on budget) since the 5.3 heads already have smaller combustion chambers. If you already have and LS6 intake and headers that should get you 400+ RWHP on a Dynojet, especially if you have a stick.