Roy Martin
the 429 cj/scj block was not the same as a boss block. the cj's were 2bolt until 71 then 4 bolt mains. the scj's were always 4 bolt mains. the boss blocks were always 4 bolt on the first 4 mains with the nascar blocks having bigger outer bolts on the front main cap. the boss deck in the lifter valley was also relieved for pushrod clearance and had screw in freeze plugs. 2 or 4 bolt 385 429/460 series blocks will take a ton of abuse.