It looks like the port side of that intake was leaking. Might be a poor gasket, or corrosion of the sealing surfaces. I would:
very carefully clean up all the sealing surfaces, be especially careful with the cyl heads, keep debris out of the intake ports. Use rolled up paper towels in the intake ports then carefully vacuum them out when done. Try not to gouge any sealing surfaces. The intake is easier, you can use a long sanding board to get it nice and flat, then check flatness with a straight edge and feeler gauges, should be at least within .003" or less. When re-assembling as Rick said use Fel Pro gaskets and I use a bit of Permatex Aviation or Merc Perfect seal or Evinrude gasket sealer on the water ports of the cyl heads and intake. It also helps hold the gaskets in place when installing. Be careful to follow torque specs and sequences. That might be all you need to do to keep water out of the oil.
What do the sealing surfaces of your manifolds and elbows look like? Since you have an older engine (pre-vortec pre roller cam) you probably have the wet exhaust joint style which can be prone to leaks if not maintained.
