Shortblock= just the engine block with pistons crank ect already installed.
Longblock=same as above but with head and usually IP
Crate engine= new everything alt, waterpump, injectors, ect. Plug and play option.

The 603 uses sleeves, if you are going through the trouble of a rebuild you might as well install new sleeves along with the pistons. The new sleeves will need to be honed and bored.

__________________
2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200