8 to 10 hrs labor to change '225' head gasket ?????

The book time would probably not include the R&R of the intake/exh manifolds. At least if I was "flat rating" it they wouldn't be touched aside from removing the fuel lines and exh pipe. That's how we used to do the 2.2/2.5Ls. So that would be a seperate charge (book time) on that.
A saavy shop owner would be thinking there's the reason the gasket blew. So the head would come off, the induction and exh manifolding comes off, and it get's sent out for milling while the block is checked for flatness. Then reassemble. They have to guarantee the job (at least in CT) so maybe that's part of it too.