The APN gives you a NEW upper with a factory-installed heat shield, reduced diameter stovepipe, a new UIM gasket and a throttle body gasket providing the best possible fix, and all for $115 delivered to your door. There is no better option.
Buy the APN and while it is all torn down, replace the LIM gaskets with aluminum frame GM gaskets, install new coolant elbows and flush the Dex, replacing it with "mixes with any color or type" long life coolant. Stick to your guns on the UIM. If your mechanic doesn't know about metal heat shields in UIMs, show him a copy of this Techinfo article: http://www.bonnevilleclub.com/forum/...e=article&k=38