Olds is kinda funny some places. You MUST have correct crankcase ventilation. IE: A PCV valve AND a breather on the opposite valve cover. If not It will puke everywhere. The easiest place is a gasket or seal. ie: dist gasket, etc. Check these.....still have the problem. check compression. You got it really hot & killed the rings?....that would cause lots of crankcase pressure (blowby ) Not likely....but possible. If leaking down the back of the block.....pull flywheel & check 3ea. freeze plugs @ cam boss. Sounds like PCV problem to me. Also....Olds pumps alot of oil thru the valve train. If you run it WOT alot, ( or even just realy higher RPM's ) lots of oil stays "upstairs" in the valley pan,etc. Combine that w/ poor vent.....yer leakin'. One trick is to put two 1" holes in the intake valley pan w/a holesaw, ( if that's what you're using w/stock manifold ). I assume (?) your dipstick / tube is correct. Old has mondo counterweight on the crank. Overfill aint good.
GregS