White smoke makes the timing of the injection pump at least suspect. You also might have two problems. From your description I would verify the fuel is being pumped properly first.

Got overflow from the relief valve on the injection pump when cranking? If not find out why not. When you pump the primer pump with the engine off is there a reasonable stiff resistance or not developed? Say there is no resistance as an example. The check valves for the primer pump are in the lift pump. Or the relief valve can be open. Or you could be piggybacking on the lift pump with the primer pump as the lift pump alone cannot pull fuel through say a bad tank filter otherwise. In other words diagnose what is wrong in the fuel supply system if anything first.

It sounds like you are basically just shot gunning or changing things with no primary diagnosis. This can get very expensive and mentally pain full. At least these cars are service friendly compared to what I ran into yesterday.

I looked at what was a simple brake line failure on my beater.. The young fellow helping me had a jack slip. Took out two lines to and near the equalizer. I told him if we could not access the nuts and get them out. Cut all the six lines and we will mount the equalizer in a higher workable position. I called the car brands dealer. .Six to eight hours labor quoted if things went well. So we should be happy that in general there are only one or two areas in these old 123 types. Plus the earlier 603 engined cars that may cause some real unreasonable difficulties when working on them.