HELP! Calling all SBC gurus

I am stumped and hope someone can shed some light. I installed a SBC 350 that sat around for about 12 - 15 years and fired it up and had 65# of oil pressure. Everything seemed to be normal until I noticed there was no oil coming out of the rockers. I pulled the right bank pushrods and rockers to blow them out and noticed there was oil in the pushrods - most were clean. The hyd. lifters pumped up and I watched the pushrods rotate while cranking engine over. I even ran it for about 20 minutes by manually oiling the rockers to no avail. I substituted another distributor thinking the base may be too small and oil leaking by there - never started it but just cranked it and watched the rockers - nada! Doubt all the lifters went bad sitting and thought if the oil galley was blocked, at least some oil would come out of some of the rockers. Any ideas???:confused:

Thanks in advance, Stumped