not the same headers but...with some doug's headers and a 360 in a 67 b-body, driver side i removed the starter, jacked the motor up a little and maybe removed the steering center link. i think i went in from the bottom. bolted the starter back up with the header kinda hanging in there..
pass side, i think i just removed the oil filter and loosened the 90* oil filter adapter and rotated it, might've slid in from the top on that side.