If it were me I'd have the head checked out by a machine shop since it's out already. Not sure about resurfacing them or not.
We have a '92 960 and had the cams off last year because of an oil leak. Allegedly there is a special tool of some kind to getting them back on correctly. This is something I heard from the shop - a very reputable place but I've never read much about this online. This is something I had to farm out due to being out of state for work.
Have you checked out
The Volvo Resource: brickboard.com yet? It's a pretty solid tech site for these cars and the forum is active enough.