I believe If I am not mistake the 2618, a low-silicone aluminum Pistons expand more during engine warm up so piston slap till she is warm but they can take more abuse. I would go with
the 4032 alloy as it is stiffer and has less thermal conductivity and expansion.
It has been a while since I have assembled an engine but I know for a fact I would do a little research before buying the pistons they typically come in 2 different alloys one expands more then the other so the tolerances have to be different for them.

And remember to have the engine block examined before purchases because there is probably a restocking fee if you don't get the right size pistons. .20 over .40 over .60 over