The one thing I have found out when using metal clad pre-tubed blanks on some of the PSI kits like this one is to dry fit before pressing on the tubes. I have had a couple crack because the slight expansion of the brass tube is inhibited by the metal cladding in the cast blank.
I sand or file off the mating ends so I can start the tube about halfway by hand to avoid heartbreak by ruining an expensive cast blank.