I'm not too sure I wanna pull the head off at this Time so I want to see if I can see if any damage has been done underneath the motor so next step is trying to unbolt the gear box from the motor so I can get the motor out and have a nosey at the block through the sump
Have you thought about putting an inspection camera into a cylinder through a plug hole or similar? You can buy them from places like Repco and Jaycar for <$200 or see if someone has one you can borrow?
Might help inspect pistons and combustion chambers without taking head off.