I have a 76 CB750A that I got in May of this Year.  Some parts (Original Muffler) are very hard to find.  I purchased parts from Bike Bandit and Old Bike Barn.  I also went to Vintage Days in Ohio and picked up a rear luggage rack with a back rest, a new OEM oil filter bolt, and a chain guard.  The chain guard was off a CB750F and had to be modified so that the rear mounting hole lined up (1/2 inch short).  I have installed a Dyna S ignition, replacing the points and I replaced the stock coils with Dyna coils.  The flasher unit ($29.95 OEM) I got from Auto Zone for $8.95.  New mirrors and trim I purchased from J.C. Whitney.  I haven't found the correct start push-button yet.  If you plan to ride on the Freeway, you may want to change the stock 48T rear sprocket to something smaller.  I went to a 38T and it reduced the RPMs.  I'm still trying to get use to the Automatic and it's cold blooded nature.  The choke is my best friend.  I have also learned to put my foot on the rear brake a rev the engine a little just before taking off to avoid a dead zone in launching.  Yes, I checked that the fuel pump is working, and I still looking through the service manuals I downloaded from Hondamatic.net.