An easy way to tell if a block was set up for truck is that it was cast with bosses for the car side motor mounts but those bosses did not get drilled out for a truck.
Would like to see a complete list of differences in the 235 from it's beginning in '41 to 63. I think that would be quite a long list. The captains bar markings above the starter for one seams inconsistant, have a 53 235 with those bars plus 261s and heard of others with a single bar or no bars at all on some 261s.