Long story short: costs are insane and merit going higher. Final project was about $40,000 after all the ancillaries. So I backed it and I've bought a 345 horse 351w with serpentine system, air con compressor and aluminium heads from Phoenix Engine for a 'mere' $13,000. But at least that should just drop straight in... without needed ancillaries. So it's a bit easier to swallow than $40,000.
The engine was meant to be here in July but now looks like August so I'm still waiting after all. I'm losing my mind not driving my 8.
So not my dream engine after all, but at 1/3 the price I decided frugality was the better part of valour.
I'll keep y'all posted.