OK....
i just waded through a bunch of posts about headspace and setback over on the files. (and several heated debates) and while reading the last one, the mailman showed up on my porch and plopped my LS on my doorstep.
heres what im gonna do...
from what i have read it seems that setback is really a preference, not exactly an issue of safety, so, ill skip the setback on THIS build, and i WILL add setback on the south african kit...then after both have been through about 1000 or so rounds i will recheck headspace on both. if the imbel shows any signs of losing headspace ill replace the LS again and i will have solved the great setback mystery! (without the mystery machine and scoob no less...)
Oh and if i dont post any updates in the next day or two...you know what happened...