Hydraulic reservoir interchange V8 to 200

[gerard]

Silly question.

My hydraulic reservoir in my 5k/200 will be replaced. Not going to get a 
brand new one from Audi, but have access to one from a V8q 4.2. Shapes a 
totally different, though. 200 is long, tubular shaped thing, but V8 one is 
a square tub.

Can I interchange? Same amount of fluid in them?

Also aiming to get the V8 brake MC sometime.

Thanks.

G.