Camplate/ Quadrant bushes

Hi all - I am rebuilding my AMC gearbox - 1972 manufacture Commando. I have the Mick Hemmings DVD . In replacing the quadrant and camplate bushes ( both equal length in my case ) do they stop at the bottom of the o-ring rabbet ( rebate on the other side of the pond ? ) on the outside of the   case ? Mick is very clear about leaving space for the o-rings and demonstrates his mandrel system for drawing the bushes in with threaded rod but does not give a dimension for this space . In the video it is clearly seen that the bushes stand proud of the inside wall of the gearbox shell when installed. Foolishly I did not take measurements before disassembly. I plan to turn up mandrels as Mick recommends but I want to be sure that my assumption that the outboard ends of the bushes lie flush with the bottom of the o-ring rabbet is correct as this will effect the amount protruding on the inside . 

 Thanks for any advice- Richard