help identifying slant 6

i just got a engine for my signet and would like to know what year it is and stuff, i found numbers on it and i think it may have been a replacement longblock at one time. there is the standard 2806830-1 on it and there are other numbers on it also. on the front of the block under the head there is a 64701C and on the pass rear pad there is 2R151921
am i looking at the right places? anyone know what it is? thanks