What's the *REAL* XK-120 cooling system capacity?

In converting this 120 to the Evans waterless coolant, I checked my shop manual for cooling system capacity. It told me that the capacity was 29.something US Pints (29.8? Regardless, less than 30).

So, since 1 gallon is 8 pints, I bought 4 gallons of coolant, which is 32 pints. I should have about a quart to spare.

So far, I've poured almost 3.5 gallons into the radiator, and the engine hasn't even been run yet to circulate it through the engine and heater core.

I remember when I removed the frozen drain tap at the back of the engine block to replace it, another gallon or two of the old coolant poured out.

So, if I've put 3.5 gallons into the radiator, and another gallon or two of the old coolant poured out of the engine block when I removed the drain tap, I'm feeling like I can't believe the shop manual notation that the capacity is 29.x pints. I've already put almost that much into just the radiator.

Note: this is a factory original radiator and has no leaks. I also don't believe there are any "problems" like an internal leak, as everything was fine when I drove the car last fall, and oil drained was free of water. This is merely a capacity question. So.....

What is the *REAL* capacity of an XK-120 cooling system?

Thanks.