I feel your pain,I bought a fernandes revival bass from a reverb seller in italy.
I think it is a 1981 model and it arrived looking in really good shape
but It also had neck issues,similar to the ones you described and the truss rod was tight
I ended up using the washer trick and that got it straighter and to complete I clamped the neck straight and manage to get some more movement on the truss rod and now its got a nice low action and plays great
was a learning curve but I really wanted to keep the bass as the neck is really nice and comfortable for me
hope yours turns out to be ok.