I had to replace my cam because I lobed the old one. I broke in the new one and had the valves adjusted. I heard a high squeal and now I have gray smoke coming from my valve cover breather. I thought the new cam was toast, so I am taking it back out. I looked at the lifters and they look fine. The oil pressure is low at idle, but gets up to 50 or better while driving. Someone told me it was blow by in the cylinders and that I need new rings. I have no loss of power to justify what they said. Any help would be appreciated.

Really not enough info in your post to 'pin-point' an exact failure.

Did you 'pre-lube' the motor after the Cam change?
Did you replace Rockers and other Valve Train parts at the same time?
Was there any "knocking" or other noise along with the "high squeal" after your start-up?
What was your lubrication sequence with the Cam install?
Were the lifters (hydraulic's?) pre-lubed or pre-soaked before install?

A common "high-squeal" noise from SBC's on start-up if they are not pre-lubed is from the rocker/pivot ball area - I would recommend you check these very carefully.
If you freely interchanged the "rockers and balls" during your tear-down or they were new and not lubricated properly during the cam chage this may be the source of the noise - they can "complain" greatly if not properly serviced. 16 of these things "singing" in unison make quite a bit of noise...

Post back with what you find during inspection and maybe we can help prevent further problems...

Hope this helped some -