I just read this that you wrote:
The lobe separation of the 911S cam is 98 degrees. The lobe separation of the K45 cam is 105 degrees. The valve duration and lift are very similar between the two cams.
So if the K45 LCA is 105 and the duration is about the same as the 911S it means you further delayed the Intake Close event by 12 more degrees! You now are giving up 62deg of compression stroke vs the 50deg with the 911s cam. The K45 cam needs more static compression to achieve the same dynamic compression with the 911s cam. This is likely why you are down on power with the K45 cam compared to the 911s cam.
Further complicating this discussion is that the 105LCA vs the 98LCA causes valve overlap to be reduced at TDC, if the LCA goes up and duration stays the same then overlap goes down. Reducing overlap helps idle quality and low RPM drivability. So I'm no surprised it idles better and takes off better at low RPMs with the K45 cam since it has more LCA.
The missing piece here is what the static compression ratio of this motor? That K45 cam likely needs 10.5:1 to 10.8:1 compression for very best results
Best book ever written on cams, octane and compression ratio is this book!
https://www.amazon.com/Tuning-Engine-Definitive-Performance-Economy/dp/1859606202
Enjoy.