Here is a really good tip for head gaskets. This is from the 350 section, but is most likely applicable to the 175. It certainly worked for me.
http://bridgestonemotorcycleparts.com/index.php?topic=4592.0Just reuse the copper gaskets. Heat them with a torch until red hot to anneal (soften) them, but not hot enough to melt. Put a light coat of copper gasket cement on both sides. I use the spray gasket sealer and lay them out on a paper towel and give them a light spray, flip them and spray the other side. Put them and the heads back on and torque the nuts to 18-21 ft. lb.
Checking the heads to make certain they are reasonably flat first is a good idea. A good straightedge will work as a check, although rubbing the head on a sheet of 280-400 grit wet-or-dry paper on a sheet of glass or a nice flat workbench will tell you a lot, also, and you can use that to true them up if needed.
