Need to make a decision fast 5.7/6.1/340

You mean these: 2003-2008 5.7 jeep manifolds ???
Will any other stock manifolds work for this a body swap?

If so, here is a set on fleabay ($100 - not mine):
http://www.ebay.com/itm/Exhaust-Man...Parts_Accessories&hash=item43ce3331b5&vxp=mtr

No, not those. The ones that look like headers. These:
[ame="http://www.ebay.com/itm/Jeep-Grand-Cherokee-SRT8-Headers-Exhaust-Manifolds-2012-2014-/281439247818?pt=Motors_Car_Truck_Parts_Accessories&hash=item4187161dca&vxp=mtr"]Jeep Grand Cherokee SRT8 Headers Exhaust Manifolds 2012 2014 | eBay[/ame]