Chalk's an odd color and I think photos will be misleading. There's been one GTS (coupe) at my local dealer for a long time, it looks white-ish outside but now they have in the showroom it looks gray. So just by human eye it varies greatly, I feel pics would not be enough to judge this color. 2c.

 

I drove beside a new Panamera 4 that was, I'm certain, Chalk. It looked great! Reminded of my Linen Grey '89, only a little darker, or more saturated. Beautiful color.

 

Chalk has a lot of beige in it. Have never seen a cab in that color. A red top would be hideous.

 

I saw one about a month ago, and it was stunning!
Here are a couple of shots I took (although they fail to convey how special the color feels):

 

Agree, chalk goes well with black top but as virage said photos may not do it justice but then I saw a chalk boxster few weeks ago and it kinda looked dirty/dull in overcast weather . chalk and carmine red are both premium colors cost wise , not sure which is the most striking as my friend has to soon decide which way to go . He went to see these cars in person and none were available in 911 cab form