I'm not 100% sure about the timing from Sato:

Can you attack with an MC30 long range, remove the 2 red dice with 2 black + 1 concentrated fire and add a 3rd black die with no red remaining even though it's long range ?

You could only add a black die with a concentrate fire command - the colour has to be of one already in the pool.

1 minute ago, Kendraam said:

You could only add a black die with a concentrate fire command - the colour has to be of one already in the pool.

The question was if the attack still happens, not about the 3rd die.

Yes. You can.

1) Gather your dice pool (2 red)

2) Use Sato to replace the 2 red in your dice pool with 2 black

3) Use CF to add one more die of a color already in your dice pool, which at this point is 2 black die

Yes, it can

Gather dice - two red as you are at long range.
Sato - remove two red dice add in two black.
Roll dice.
Add black die from concentrate fire dial if desired.

Yes, the attack does happen. And yes, with a concentrate dial you will have 3 black dice.

Edit: after i was so slow with the answer, i will at least present some ruling to this

This is the important part:

Quote

2 . Roll Attack Dice: Gather attack dice to form the attack pool and roll those dice. Gather only the dice that are appropriate for the range of the attack as indicated by the icons on the range ruler.

◊ If the defender is a ship, gather the attack dice indicated in the attacking hull zone’s or squadron’s battery armament.
◊ If the attacker cannot gather any dice appropriate for the range of the attack, the attack is canceled.

You gather the dice from your battery (two red).

Because you have at least one dice the attack is legal (and remains, it, as long as you have one dice left in the attack pool).

After this (and before you roll any dice) you remove up to two dice from the pool (the red once) and add the same number black dices. The attack is still legal, because you still have dice in the attack pool.

Only the first collect of the dice, the one with the battery armament, is important.

You got the answer yet but just to point out the timing:

1. gather the two red dice

2. change them to black before rolling with Sato

3. roll the black dice

4. add your CF. As you only have black you must add another black die.

If you want a red die, let's say cause you want an accuracy or whatever, but you want black dice too you could...

1 gather your red dice

2 change 1 to black with Sato before rolling

3 roll

4 add your CF. As you have 1 black and 1 red you can add whatever you want but blue. Add your second black and do whatever you want with your red die (TRC, HomeOne, H9... shit! I will hate Sato)

Thanks a lot!

Note that Sato can change the dice to any color or colors . So you could:

1. Gather the two red dice

2. Change 1 die to black and 1 die to blue (for the accuracy, or in case you want to be able to trigger Leading Shots or some other ion upgrade)

3. Roll the dice

4. Use CF to add extra blue or an extra black depending on the outcome of the roll