I meant that the ISCV wont interfere with the tune.

The ISCV lets air into the vaccuum manifold, with will change the map sensor reading. But this isn't a false reading, you want the MAP sensor to pick up the difference so the fueling is accurate during idle.

The booster, on the other hand, will change the map reading when you press the brake pedal. This could lead to inaccurate fueling during idle if you start pumping the brake when your car isn't moving. I just wanted to point out that you don't necessarily have to do anything about it. Most of the time when you pump the brake pedal, the accelerator is off, and you are therefore in fuel cut.
Not only that, but you should be most concerned about accurate fueling during full throttle open loop conditions. That's not a point when the brakes are commonly pumped.

But, that isn't to say it's never an issue. Like, for example, bedding in brake pads. I'm not sure how people have solved this issue for 16v ITB conversions. But in the factory 20v setup, the booster has a source of vacuum independent of the vacuum manifold by being connected to holes in the runners on cyl #1 and #4. The fuel regulator and the smog gear is also run from seperate vacuum holes. But everything else, including the ISCV, is connected to the one manifold.

Also, I'm using a silvertop as a reference, so I can't speak for the blacktop's map sensor, I'm afraid. If I were to use one on my silvertop, I would connect it directly to the vacuum manifold, though.