Sounds like you will be moving a large quantity of fluid to get them working.
Will you be fitting the uprated master cylinder?
I take it the 345mm disc is from the R32? What wheels can you fit with them?
The R8 calipers has a slightly smaller piston size which im assured by 'The Guru' will work fine with the standard master cylinder. If I dont like the feel then I will upgrade. Doing a cylinder change isnt a quick job though.
Ive not tried them on my wheels yet, but it will be 18's or larger to get them on. They dont fit with my winter wheels which is a bummer.
The DaveB brackets allow the caliper to fit with the standard 345mm discs