I have seen the exact same combo on an older model (early 80's)
It actually looked great, so go for it. Orange/black go well together, I had few KTM motorcycles and that's the color scheme they use.

 

I wouldn't do it but I would be happy to see that someone else did. I think it's fun and if you have the huevos, than good on you.

 

orange or red looks good on a GT3/GT2 but on the 997 thats different. I had the same thoughts on changing the rims color on my old 997 this aluminium standard doesnt look nice actually I hated it
just go for black or grey with a red or aluminium edge.. posted some pics
good luck..

 

gorgeous!!!

 

The Orange and Red really standout but I am still partial to a grey/sliver that just flashes those red calipers....