Hey Mark
yes we use cast iron threaded rod for the 2x end stud plugs, we gave Jspinx the nod on that lot years ago, (along with a pile of guys in the UK that we helped sort plugs for as well)
& we also use the CNC mill to drill all the new holes dead true to the crank center-line
it`s easy with the right know-how & the right gear hey?
& yes the SC build guide is very very poor, i think they`d rather customers pay them to do the whole job than give them the knowlege on how to do it themselves
anything you need just give us a bell mate, happy to help,
weve had a couple of SC jobs come through here & they were both a total pain.
& we have another one here now too, not fun but has to be done