any way to tell what CID it is

Sweet i found the CID its a 400. Maybe if the mopar gods shine their light upon me its a 451. One can dream cant he. Anyway There is another number near its L 77 i think. is this the year? and are 400's any good to trick out, I know alot of trucks came with them. i know alot of you will say you have the block get the crank (451) im looking at both options. What all is involved in the 451
thanks