When Goku was about to fire the KHH, he said, "Please, let him be bluffing this time." That implies that if Freeza is bluffing and cannot increase his power any further, the 20x KK/KHH is expected to deal him serious damage.
As we saw earlier with Recoome against Vegeta's pseudo-final flash, a blast that is around the target's PL does not deal serious damage. Therefore, for Goku's expectations to be reasonable, the 20x KK/KHH combo must be visibly above 50% Freeza.
Goku 20x KK - 9
Freeza 50% - 10
Goku 20x KK - 12
Freeza 60% (catching the blast) - 12
Freeza 70% (stopping the blast) - 14
FP Freeza - 20
SSJ Goku - 22.5
Another approach is to accept that the full KHH multiplier (which is 1.5x in my books) is applied to the already multiplied by the kaioken power. In that case, Freeza has to have powered up to 70% just to catch the blast. Then we accept the filler part in which Freeza counters with a blast of his own as canon.
Goku 20x KK - 9
Freeza 50% - 10
Goku 20x KK - 13.5
Freeza 70% (catching the blast) - 14
Freeza 70% (counter blast) - 16
FP Freeza - 20
SSJ Goku - 22.5
Alternately, we can accept as cannon the filler part with Freeza (when beating up Goku) saying he's only using a third of his power after all.
Goku 20x KK - 9
Freeza 33.3% - 10
Goku 20x KK - 13.5
Freeza 50% (catching the blast) - 15
FP Freeza - 30
In the last case, we need to increase the SSJ multiplier to 60x.
As we saw earlier with Recoome against Vegeta's pseudo-final flash, a blast that is around the target's PL does not deal serious damage. Therefore, for Goku's expectations to be reasonable, the 20x KK/KHH combo must be visibly above 50% Freeza.
Goku 20x KK - 9
Freeza 50% - 10
Goku 20x KK - 12
Freeza 60% (catching the blast) - 12
Freeza 70% (stopping the blast) - 14
FP Freeza - 20
SSJ Goku - 22.5
Another approach is to accept that the full KHH multiplier (which is 1.5x in my books) is applied to the already multiplied by the kaioken power. In that case, Freeza has to have powered up to 70% just to catch the blast. Then we accept the filler part in which Freeza counters with a blast of his own as canon.
Goku 20x KK - 9
Freeza 50% - 10
Goku 20x KK - 13.5
Freeza 70% (catching the blast) - 14
Freeza 70% (counter blast) - 16
FP Freeza - 20
SSJ Goku - 22.5
Alternately, we can accept as cannon the filler part with Freeza (when beating up Goku) saying he's only using a third of his power after all.
Goku 20x KK - 9
Freeza 33.3% - 10
Goku 20x KK - 13.5
Freeza 50% (catching the blast) - 15
FP Freeza - 30
In the last case, we need to increase the SSJ multiplier to 60x.