It is indeed 68 as per round side marker lights.69 had square reflectors and 70 had squared lights. It is a big block, can't tell if raised block (440,413,426 edge) or low block (361,383,400) there is a pad next to distributor that will show CID. also if paralell to intake valley rail, it is RB. If it is paralell to head surface it is B engine (low block)
