UH'OH Caveman, i made a mistake, the PC's are not closed chamber, sorry my mistake. I think Dart makes a set of closed chamber, round int. runner and i think my friend has a set of them, he's going to take a look at them and call me back in a couple hrs.
Sorry for misleading you on the PC's.
Zip.
There's lot's of closed chamber heads listed on Ebay for sale, most are large ovel intake runners. I ran a set of these heads in the mid 80's on a 427 in a 3500 lb Chevelle and it ran low 11's. Here is a few of the listings.
http://www.ebay.com/itm/BIG-BLOCK-CH...sories&vxp=mtr
http://www.ebay.com/itm/Big-Block-ch...sories&vxp=mtr
Now here is the real deal on closed chamber heads
http://www.ebay.com/itm/RARE-BIG-BLO...sories&vxp=mtr