Your photo is basically a "poster child" for overheating culprits. In no particular order I will address them.
1. Aluminum does not conduct heat as well as Brass, so your Aluminum radiator will not be as efficient as a stock 3 row. --- This would not be a problem if everything else was designed to work with it, but it's not.
2. Without a factory (any brands factory) designed shroud, you will almost certainly overheat, as the manufacturers spent Millions to design an efficient fan/shroud/pump volume-speed setup. --- The mid thread photo of a "suggested" dual fan/ flat aftermarket shroud will only contribute to your problems, as they act as an air dam as speed increases.
3. You have an electric water pump. They will flow about what a stocker will at low RPM; but can't flow enough to keep a performance big block cool at anything but idle (that’s if you had an effective fan/shroud set-up), They are generally sold as race set-ups, and really aren't any good for even that.
4. You have a non-vacuum advance distributor. These can work fine if the engine/car is designed for them, but if I remember correctly, you said it was set up for 12 degrees initial. That would work for idle (if everything else was set up for that), but will be extremely retarded at anything over completely stopped with no throttle opening. --- Retarded timing will contribute substantially to overheating (as well as poor performance) even with a workable fan/radiator/shroud/water pump situation.
5+. Even if you had a workable system, the radiator is not sealed to the support, Your "rated" fan CFM is marginal at best, and probably only half that, It appears as though you are using either a chromed, or polished stock alternator, which simply can't produce enough power to run a good fan, Those "lever-vent" radiator caps are not a good choice due to there variances in "actual" pressure, and basic inability to retrieve coolant from the overflow tank.
6. Unless you are running a coolant that has a high silicone content, and you have made certain that you have no residual voltage grounding through the aluminum radiator, your cooling will very quickly degrade in as little as a matter of months, and your aluminum radiator will be useful only as a paperweight.
I can't offer you any solutions unless you are willing to start from scratch, and sell off 90% of the stuff pictured in your photo.
You can change to the stock system, which will be an improvement, but you can produce stellar improvements over stock (just like changing to disk brakes from drums), if you are willing to change over your alternator in order to run it.
Lastly, I only point all this out as a guy that was born, raised, and (for decades) live in the desert, so I had to learn what makes a cooling system work, with A/C, in as high as 126 degree temperatures, while maintaining as much performance as possible.
Your environment is infinitely more forgiving than mine, so you can solve all your cooling problems by simply going back to basics, and improve upon them if you want, but like I said in the beginning of this post, your current system is not functional as it stands.
