Do the normal checks of rocker cover gasket, oil pan gasket, cam gear cover gasket. All gaskets can fail over time, it's the normal life cycle of a part.
If the piston rings and/ or cylinder are worn beyond specifications then you will also get excessive combustion blow by past the piston and the excessive crankcase pressure will cause excessive oil to be forced out of the crank case breather and possibly blow out a gasket as well.
Here is a parts diagram of your engine for reference:
If you find that you need a whole new engine, Staton is a very reputable dealer that many here support: