Thanks again for sharing your expertise, Klaus.

I don't think I mentioned, I purchased the '99 XC with a salvage title from body damage. We had major service done right away, including fuel filter change, cleaning of throttle body, and the air filter was deemed in great shape. The major repair done was replacing all 5 ignition coils. Compression was deemed at that time to be all in the right ranges. After that major service, we put on about 1000 miles, when the valve broke.

Options are, $5300 for a repair to the existing cylinder/valves, with all the required stuff that goes with that.

Or, $1800 for a warranted engine from an internet site, one with about 65K miles on it. Parts and labor to install at shop rate.

Or, the salvaged engine from the '98 FWD S70, installed whole into the '99 AWD XC.

Or, the head taken off the '98 S70 and put on the '99 AWD XC. I think this is the most expedient and possibly the best choice mechanically? It would disturb a lot less.

I'm advocating for the last option.
At this point it's a matter of someone convincing the shop service writer that the turbos are compatible.