To carry the discussion a little further (hopefully in a positive, helpful way), there is always the desire for "margin", in this case, cooling capacity in excess of the original design specs or capability.
Pantera owners search for "margin" a lot - look at horsepower, brakes, tire sizes, and upgraded shocks/suspensions, for a number of relevant examples.
I think the coolant mods can certainly give owners "margin" in excess of the original design (and with it, confidence). Certainly it is hard to objectively quantify how much improvement you gain - especially with modifications to an already functioning cooling system, but.... who would argue that a system that AUTOMATICALLY bleeds air out of the cooling system (both at the radiator, and at the swirl tank) is a bad modification - especially when we know that air trapped in the cooling system can have adverse consequences?
I would agree that the first thing an owner should do is ensure his original cooling system is working as best as possible - but then... why not add margin? We Pantera owners do it all the time.
Anyway - I hope The Captain can find someone with a TIG torch and SS rods. The changes are pretty straight forward.
You can probably buy bungs, and brass bayonet fittings on eBay, and just give the fabricator the two tanks, and say... Make this one like that one.
Good luck.
Rocky (a.k.a. Chuck)
PS> The name of my Toyota FJ-40 Land Cruiser is "Rocky", so that is how I selected my forum name.