For the avoidance of doubt it is impossible to install any firmware on the iPad without a valid set of SHSH Blobs for your device and the version of IOS you are trying to install.
Since you don't have 4.3.3 blobs saved, and Apple will not supply them any more, you are out of luck I'm afraid. The only firmware you are entitled to restore as things stand today is 4.3.5. Sorry.