Block.blockState is now Block.stateContainer.
As stated in my previous reply this is done through a builder now.
CreativeTabs is now called ItemGroup.
As stated in my previous reply EntityRegistry is gone.
I don't know where you were importing FACING from but you can get all vanilla blockstate properties from the BlockStateProperties class.
Instead of a single IBlockAccess there are now a lot of various interfaces that the world implements. I don't know which methods of yours needed the IBlockAccess so I can't tell for sure what it needs now but I suspect it needs a IBlockReader.
As far as I can tell from your code that points into your main mod class so you've removed that field yourself.
As stated above this is done through a builder now. Also that syntax was never needed in the first place.
PropertyDirection is now DirectionProperty.
Again, that points towards your main mod class, you've removed the field yourself but left the reference.
As stated above this is done through a builder now.
Instead of a single IBlockAccess there are now a lot of various interfaces that the world implements. I don't know which methods of yours needed the IBlockAccess so I can't tell for sure what it needs now but I suspect it needs a IBlockReader.
As stated in my previous reply this is now done through Block#fillStateContainer
Since metadata is now gone those helper methods to convert to and from metadata are gone too.
IBlockState#getValue is now IBlockState#get.
Block#isOpaqueCube is now controlled through it's VoxelShape returned by Block#getRenderShape and simply checks if the given shape is a full cube. It will also return false if Block#isSolid returns false.
Since hardness is now final the setters are gone, use Block.Properties passed to the constructor to control it.
Same here.
And same here too.
Unlocalized names are now gone. Instead they are controlled by Block#getTranslationKey which uses the registry name (block.REGISTRY_NAME). This is done for you automatically, you don't need to set anything.
IBlockState#withProperty is now IBlockState#with.
I don't know what you were using this for but be wary of an ongoing issue:
https://github.com/MinecraftForge/MinecraftForge/issues/5470