drock,
Flat oil usually requires early rolling balls with (or drilled for) minimum backends. So your saying that people used Black Widows and No Mercys surprises me, as these are balls with big backends, which reduce the amount of control normally needed for flat oil.
The NV is an early rolling ball requiring lots of oil, as far as I know; so those sorts of balls from Lanemasters/Legends include such as World Class Reactive & Masterpiece (for medium oil), NS2 (for medium to medium-heavy oil), and World Class(particle, for medium-heavy or more oil).
Other LM/L balls can be made more even reacting by drilling options and/or surface changes.
How you might have to drill them depends on how "flat" the oil actually is and your other deliver/release specs (tilt, rotation, ball speed).
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"None are so blind as those who will not see."
