no piston size stamped on cylinder?

[stainlesscycle]

i was planning on ordering a top end kit for my 99 300 top end. i'd like to order before i tear apart. the cylinder has no letter stamped on it. i would assume a 'b' piston will work in a and b cylinders - but if it's a c cylinder - will i get slap with a b piston? i know the difference in sizes is only .001.. i would think the letter designation is not so crucial on an older well used cylinder.... (i might even get it open and see it needs relined anyways....)