As I understand it, the accepted method for killing powder post beetles is bringing the temperature of the kiln above 130deg for at least 6 hours. Would a vacuum kiln that pulls 29.5" wc and then gets heated to 80deg also kill powder post beetles?
Given that there is no way to 100% keep powderpost beetles from entering your home, even with professionally cured and stored lumber, what you are doing is trying to minimize your exposure. Control of these pests is through depth, rather than a single solution.
I'm going to say that, within some reasonable hand-waving, your mitigation technique will approach some level of surety that the lumber does not contain these pests.
I'd go further. The advice given by many pest-control folks is:
- If you use untreated wood that has been stored outside, you need to treat it in some manner, as described in your Question. However, even industrial kilns can't guarantee there aren't powderpost beetles inside lumber.
- Wood should be kept below 12% moisture, as 12% and above is what the beetles need for their life-cycle.
- Finish your wood projects that use this lumber with a "coating" finish. e.g., shellac, paint, or varnish of some sort (or equivalent).
The fact is, in some areas, you may already have these pests in your home, never mind in the furniture or lumber you bring into your home.