The man wants MORE caster. How about this idea?

I wish that I knew an alignment guy that liked to tinker in his free time.
I estimated adding 1/4" just as a starting point. Something like this could be mocked up on a test chassis and measured and recorded. The tubular arms that are purported to add up to 3 degrees or more could be measured, "mapped" so to speak and then the stock arms could be measured to compare.
I have a buddy's car in the shop out back, a '68 Satellite with Firm Feel UCAs. I could measure them and compare them to my stock arms on the shelf.
For example, take the stock arm below...

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I could measure between the zerk and the forward bushing and the same between the zerk and rearmost bushing and then compare the numbers to the Firm Feel arms. Just some bonehead logic at work here but I'd suspect that the aftermarket arms would have a longer front measurement than stock and a shorter rear number, effectively moving the top of the spindle/knuckle rearward.
By the way, what so many people call a spindle is actually a steering knuckle. The spindle is technically the horizontal section that the hub and brake attach to. Most people call the whole thing a spindle, just like how "emergency brake" gets used to describe what is actually a Parking Brake, a Sure Grip gets called a Posi, etc.