Mick,
Just to back you up, when I was assessing with AAMI, I did an assessment on the very first smashed VS Commodore requireing an entire Bulk Head replacement, when the beater rang Holden for the parts, there was an alert sent out by Holden, this was the first reported bulkhead change, problem was these things wernt welded in but urethaned, these days they all are.
Long story short, Holden techs came out to oversee the change over in workshop conditions, the bulkhead was pre-painted by the shop, and glued in place, all went well.
These days the entire dash wiring on Commodores and falcons are pre assembled on the bulkhead and glued in place as a single assy on the line.
This also means that a lot of new cars are written off for the pure fact that the process of gluing in new bulkheads is a serious process, and most cars hit where the bulkhead is only slightly warped cant be beaten and welded up at a skirt rail intersection, you must replace the entire assy.
So if you are looking at a smashed car at the auctions beware, there is good reason why they were written off to start with.
This has been Panel Repair 101 session 2 presented by Mick and John.O.