if the Blitz 4 did not come with the slave cylinder, take the clutch pushrod out and make sure they are the same length... if your blitz4 did not come with the slave, and you are going to have to use the one off of your old engine, more then likely your going to have to use the pushrod out of the old engine... so long story short, if using the old slave, use the old rod as well (if the new one isnt the same length) Other then that you should be good to go
Dave