Well I doubt it has been rebuilt depending how old you are , probably just pulled out & left , I tend to think the other way , the early blocks were weaker & did not have the extra rib at head bolt depth so in my mind the later blocks are better some had steel cranks , not the heads though they got worse with 67 being the best . A quick look at the damper will tell , 1" thick is steel , thicker is cast which make zero difference if you are going to do a stroker build anyway , also a E stamped on the top pad indicates cast crank if it is cast after 71 .
has to worth $500 + in decent shape