I built a 326 a few years ago too- the owner also wanted to use the stock heads too, but when I heard his power expectations we both knew better heads were needed. We opted for KRE D-ports milled to 58cc and fitted with 2.05/1.66 valves. The chamfers did need to be repositioned to work with the KRE heads, but it was well worth the effort.
Cam selected was a Comp cams XE 268H- it has your typical lopey Comp cams idle, but it still works with the power brakes. Stock Sealed Power pistons were used for different reasons, but 4340 H-beams were used along with the stock crank to help the rotating assembly balance without Mallory metal. The block was also decked and SCR was set to 10:1. We also used the Victor-Reinz 3401VC head gaskets. The 326 was finished off with a port-matched performer, Holley 750 Vacuum secondary, and Hooker Comp headers.
So how did this build turn out? The owner loves it, and has trouble convincing people it's only a 326 and not a 400. Imagine what this little 326 could do with some head porting and a roller cam. The 326 has alot of potential most Pontiac owners never realize.
