Hello Andy,
I have replaced my rear shocks on my '74 cb750 K4 without loosening or removing my exhausts.
I loosened the bottom bolt of the shock as much as I could. Then I placed some rags against the chrome finish of the exhaust pipes. You should have the shock absorber's top bolt "cap" off; it will help in the positioning of the bottom part of the shock. Then I pryed gently and judiciously with a prybar against the rags on the exhaust; the bolt came out, the shock came off. I used the same method to reinstall the bolt on the new shock.
Never had any problems, nothing got "tweaked." I believe I saved myself a lot of unnecessary headaches and work. It was a fine fix for me; I think it should be able to work for you........
~ ~ ~ jaknight ~ ~ ~