ya, do the guides and tension while your there.
I did the chain on my 450 several years ago. The replacement chain has a master link. So you secure the old chain to the spockets with some plastic zip ties, then cut the chain (don't let the chain slip). Use the master link to connect the two together. Hand crank the engine to snake the new chain into place.
It took me about 12-14 hours, so I would think a shop could do in 2-3 hrs.