Here are a few pics I had from my 79 403. The top one shows that I removed the EGR valve and made a blockoff plate from some steel plate(ignore the yellow arrow..that was for something else). Use an EGR gasket under the plate. Plug the pipe on the carb labeled "egr".
The 2nd pic shows the vacuum hose routing illustration for a 79 403. You don't have to connect that SVB-TVS thing. Instead, connect the rear vac break hose to the manifold vacuum pipe that's on the back bottom of the carb.
And the 3rd and 4th pics show where the vac hoses go on the carb and charcoal canister. The numbers on the canister relate to the numbered ports on the carb. This works fine if the charcoal canister is in good working order. My canister apparently has a bad check valve which made my engine run rich. So, I disconnected the canister hoses at #2 and #3 from the number #2 and #3 vac sources on the carb and intake and plugged those ports. Those vac source were sucking in too much gas fumes into the carb and intake causing a too rich condition. The #2 and #3 canister ports can stay open or run hoses from them to under the car for venting. I kept the hoses for the vent line from the gas tank and the fuel bowl vent(#1) connected to the canister. Works very well that way.