If you are certain that you will not need more than 32GB of RAM, then go ahead. Although in that case I’d recommend getting 2x16GB instead of 4x8GB, so you can upgrade should that be necessary.
In terms of the GPU, I based my choice on the assumption that some of your applications can use CUDA or otherwise use the GPUs performance. If that is not the case, then a RX580 will do just fine. Of course look around before you buy, for example sometimes RX 590 can be found at a similar price while having about 10% better performance (source).
As for the CPU, unfortunately that is not quite as easy to answer. If we look at this benchmark of Photoshop CC, you can see that the AMD CPUs just barely beat their intel counterparts. The Holomark benchmark in rhino even shows the 9700K at the top, ahead of the 3950X, which has 2x more cores and 4x more threads.
If you want the best value my pick would be the Ryzen 7 3700X. It will overall perform very similarly to the 9900K, with either one getting a small advantage depending on the application.
One major advantage of the 3700X is the lower heat output, so you will not need quite such a large cooler and you could likely even get a smaller power supply.
If you do choose to go AMD try to get the fastest memory possible, I would suggest at least 3200MHz, as it can make a significant difference (source).