1966 Barracuda door latch issue

So I have begun the cleanup on one of the 66 Barracudas I recently drug home. This car is over all really really solid. I got the outside cleaned up as good as I can for the moment, and I need to get to the inside. Unfortunately it seems the passangers side door latch seems to be seized up fro Not being opened since 1989. I have been trying to soak the latch mechanism in Gibbs brand penetrant. From The outside and the inside of the door. I was able to to get the passenger door panel off without destroying it with the door closed. Anyone have any tips or tricks for getting this rotary latch freed up to open? Thanks in advance for any assistance.

Jason