273 Head Cracked????????

I need advice! My engine is in for rebuild and
thinking about the oil symptoms before I pulled
it it seems possible that there is a crack between
one of the oil galleys to the rocker assy's and an
exhaust port. The plugs all had a clean burn pattern
as did the valves but on startup it would spit a couple
ounces or less of raw tarry oil out the tailpipe onto my
floor. Any suggestions?
TIA, DR