Nice find,and good looking Original CX tag as well.
I wouldn't balk fo a minute on that engine timeline,it all seems acceptable.
Even that Trans. falls into perspective.
C=Chevrolet
X=Solid Lifter engine applications
69=Model year
2160=Serial No. My records show this falls into the right time line.
395=Assembly day starting with January 1st,1968 which decodes as Friday January 30th,1969.
Just curious..Have you thought about hunting for the Nova itself these came out of?