Get the Upper Intake Manifold from here.

GM Intake Manifold Kit - iNeedParts.com

Its only 89 bucks and has a metal sleeve around the melting prone area and a smaller stovepipe, so there is a space between the mani and the stovepipe. No more melting.

The Dorman intake is 135 bucks and it also melts and is no better than the GM manifold, from what Ive read.