Note that some of these cars have blue ribbons on them.
I think if you choose a non-alfa color, some will rant wildly (well, gently, this is a very civil BB). Others will tell you that you should do whatever you want to your car.
Look for the posts of Ossopedia - he may have the most perfect restoration job (still in process after many years), and certainly the best collection of photos.
And Akitaman's work as a professional body and paint man is super - he too has a few threads.
Just decide what you want of your car and go for it. I seem to find most italian cars of all makes turning farina red after 20 or 30 years. Muts be some property of old italian paints.
Be sure to look into the sill, floor, and fender arch rust - the most common spots for problems. The sills are especially critical for a spider as the entire front-to-rear structure is carried here.
It takes a lot to properly change the color of a car - door jambs, trunk and engine bay, etc. But maybe you just want a quick exterior job. A few here have even had an Earl Scheib job for a few 100 dollars.
A non standard color will affect the resale value. But alfas are not investment cars anyway - they have always been drivers cars for those of us that like to be different.
Enjoy!
R