I'm not familiar with the exact site you wish to dive, but it's a very well known fact that hundreds of people have died in caves. It's a well known fact that a large percentage of that number were open water instructors, and others with a lot more experience than you claim. It's a well known fact that the number one killer in overhead is lack of training.
I would avoid overhead situations at all costs unless you have the proper training for overhead diving.
I would avoid overhead situations at all costs unless you have the proper training for overhead diving.