John,

For reassembly, you slowly screw in the 6 rocker-arm posts. You have to make sure the push rod ends stay in the ends of the rocker arms as you tighten down.

Make sure you have the rocker arms in the correct order - try not to disassemble the rocker arms/springs from the hollow shafts/rods. The 1960 rocker arms drawings and instructions are on pages 8-9 and onwards. 8-11 and 8-12 have terse instructions and a few photos.