Leak/crack/hole in fuel pump diaphram would definitly pump fuel into crankcase. Top of fuel pump should have a "pee" hole (small
hole) that wil shoot a small stream of gas when the engine is running so you can be alerted to the problem. Check to see if your pump has this hole, and that its not plugged.
Sounds like the engine wasn't run much, so gas varnish build-up is a prime suspect. This will cause the needle to stick in the open position and flood the engine with gas which of course adheres to the law of gravity, and heads straight to the
oil pan. Also, if this thing has a holly carb. the accelerator pump check ball will be stuck shut, causing the " bogging" when you try to accelerate.
Only two ways to get gas in the pan: Carb flooding and leaking fuel pump diaphram.