The booster is correct, it's hard to remove the valve covers on these trucks with Air condition, the line out of the compressor gets in the way, trick is to twist the valve cover up the carb and pull forward.

Both my Midnite Express and the Green 78 Warlock read 2 quarts low when filled, the Midnight my dad had back to Reedmans a few times, a few dipstick tubes and indicator sticks later it still was off.
My Black 74 was also off when I bought it, but after some bending and persuasion it's fine now.