I just completed a compression test on the fresh 400 in my 65. What promted me to do it was oil on 5 or 6 of the plugs, the threads that is. Results were surprising. Only 80 lbs. give or take a couple. This motor has been completely gone through and has only about a hundred miles on it. There was a heating problem with it intially but have that under control. I never let it get over 220 before shutting off. It has 6X (8) heads with new bronze liners and KB silver lite pistons with the included chrome rings set. The block was decked to .005 down the bore. The cam is Comp XE262H-10 without much overlap. Will this thing eventuually seat the rings or should I pull it and rering it???  

Chrome rings take longer to seat than moly or cast iron.  Make 2 or 3 hard drag strip (or equivalent) passes and recheck the compression.  You could also do a leakdown test (<15% is good). Any good auto repair shop should have one of those testers.

If leakdown is good, but compression is low, consider that maybe the cam timing is off by one tooth.  

Ok do you know the part number on the rings I don't think they sell chrome moly rings any more because they eat cylinder walls also do you know what grit hone they used.  

THE RING SET PART NUMBER FROM SUMMIT IS
SLP-E-299k030. I WILL CHECK WITH THE MACHANIST TOMORROW FOR THE STONE GRIT HE USED TO FINISH THE BLOCK. PISTON PART NUMBER IS UEM-KB133030-8.  

Hey Pontiac Man. You are right the ring set is moly faced iron set with stainless oil rings. The machinist used 200 grit stone to hone the block and uses 260 for 3 light passes to finish the job, all done with the torgue plate bolted solidly in place. I'm beginning to think the cam is advanced and causing some of the compression to be bled off. The oil control is still a concern though. With only 12 lbs. vacume I think the PCV is sucking oil and making the problem.  

Something is not right here, with that cam you should have way more than 12" vacuum. I mean we are taling about a freshly rebuilt 400 that is almost stock spec, it should pull closer to 20". Are the plugs oily? If so, all of them or just some? Try plugging the PCV hose to see if the problem goes away, remember to keep the breather so the crankcase can breathe. What about valve seals, I had a SBC with a high volume oil pump and a nearly stock cam that put so much oil up top that the vacuum was pulling oil down the brand new guides, we solved it by installing positive umbrella seals instead of the o-rings on the retainers. I would suspect cam timing as the source of the low vacuum. Just a few other points to consider.
Steve