Depends on the year of the block.
If you look at the Chevrolet parts and Accesories book, you will find that the 54-55 used a different lifter than the later engines. It doesn't say, but i believe these were the "milk can" type. Should have one groove around body.
The 56-62 engines used the shorter style that most of us are used to.
I would also advise you to stay with solids. The 235/261 engines often have bleed out problems at sustained rpms when using hydros. If you do decide to switch to hydos, then you will want to change the camshaft also.
