Don,
Just a quick tip from me, having built two LE this past weekend.
What I found was that it's easier to mount the Heatsink to the PCB first using the screws and plastic spacers.
Once the heatsink is mounted to the PCB, smear a little heat sink compound just under each hole where the screw goes through the heatsink to attach each Triac to the heatsink (rather than trying to smear some heatsink compound onto each Triac and then mount it to the heatsink).
After smearing the heatsink compound to the each of the Triac screw holes, slip each Triac into the PCB holes and then gently push them into the PCB holes and then push the Triac tabs against the heatsink which then spreads the heatsink compound evenly on each triac, push a screw through the Triac hole, through the heatsink and attach the nut to the back of the heatsink (don't tighten the nut yet)
Repeat this for all the 16 triacs and then tighten the screws and nuts to hold each triac snugly to the heatsink.
Afte this is complete, turn the PCB over and solder each triac leg to the PCB and then trim the leads of the triacs.
Using the above method made it easier and cleaner for me.