#2 stamp on block z1-kz each jug

i found a 2 stamed on each cylinder on top of the block where the head gskt sits..this is the same 2 as stamped on the big bore block that i will install..what does the #2 stamp signify???thanks peace craig

amount of decking or overbore?

and the stamp was factory installed for future reference...

probably rebuilt at some point

thanks..no expert on piston i.d..but i really thought the doming and finish looked stock on the motor i'm unseizing and it has the 2 stamp also and same type stamp(that's what got me thinking oem..the big bore block has a 2 and the iron sleeves visually have less meat left than the seized motor..i'll measure the pistons..thank you