I do several cylinder head overhauls a year. I have built a jig to compress the springs and a plate which holds the valves on the seats while compressing the springs from above. The intake valve seals are best removed with a tool designed for that purpose as they sit inside the well for the bucket. The early heads use an 11 mm pipe plug at each end of the oil passageway, and they should be removed for cleaning. The later heads have a socket head screw set into the head and staked, and these are much more difficult to remove. The camshaft should be released carefully and gradually from its five caps - the shop manual says you must use a tool to hold it down to prevent it snapping, but I have never used one and never snapped a cam. The cam seal is easy to install, use new dampers and valve seals, have your machinist adjust the valves by grinding the stems to length (like the old Ford flathead V-8's were done) and ignore any out-of-flat condition less than about .007 inch. The high torque values will flatten the head on the block no problem. Elring make the OE gaskets, but lately I have been using Victor-Reinz gasket sets and they seem to be very good.
Volvo advises 44.5 degrees on the valve angle, and 45 on the seat. I use 45 on both, and lap the valves before final adjustment. That way the valves maintain the adjustment just about for ever.