Noob rebuilding rb. Main bearing question.

[Zrb26]

Hello I have a rb26 from I believe a r32. I bought the engine a while back completely disassembled it not knowing what to do so I left it like that for a bit. Now with more engine knowledge I think I’m ready to start working on it. I want to start with just getting g the crank and pistons back in. So I found some bearing from enjuku racing. But they have 3 different sizes and I have no idea what size to get. What do I measure to figure this out.