They used coolant for choke heat through the 76 model year, it was a bad idea even back then. In sub zero weather you could drive 3-4 miles and still be on choke and running rich with the cat giving off a nice warm red glow, not to mention lousy gas mileage. An electric cap off a later one will fit and should be fed stator voltage from the alternator. The vacuum advance can be done 2 different ways
1) full manifold vacuum from below the throttle plate will give slightly better gas mileage if driven with a light throttle, at the expense of a low speed surge and loss of power on hills and hard accell. (2)Ported vacuum from above the throttle plate like you have it will add advance as you accelerate and run smoother throughout. The EGR is fed externally by a tube that runs from the exhaust manifold around the back of the engine and into the bottom of the EGR spacer. The vacuum for the EGR is from the EGR port on the carb which acts similar to ported vacuum but supplies less, it also goes through a TVS(temperature vacuum switch) that will prevent it opening until the engine is warm. I would not hook up the EGR because it will likely stick open from carbon build up while it was inop.