[cancunia]

I don't have experience with your engine, so just some thoughts about how to proceed.

I would try to turn the camshaft & crankshaft independently of each other a little at a time, if the camshaft gets stopped, maybe turning the crankshaft back or forwards a little will allow a bit of forwards movement on the camshaft.

If you take the cam belt off, can you turn the camshaft sprocket forwards, then follow with the crankshaft? I don't think turning the camshaft backwards is a good idea due to possible issues with a camchain tensioner but am not certain about this. You should be able to turn the crankshaft backwards a little though, as you've already done this to some extent.