Wheels are personal choice ...if money no object and I cound find a set Id have genuine gas burners ...
It's actually the other way around, Fuchs 17" replicas are the ones and the cosmics are old, well not old 3 years not a mark on them and I've just put new rubber on them So far I think the Fuchs are my favourite but I think I will get them detailed
cosmics are ok. 17"s look too big for a bus IMHO. They would look better detailed i think. This one has 7*17 repro Fuchs like yours but detailed: more info here: http://thelatebay.com/index.php?threads/my-westfalia-1977-with-fuchs.2009/
17" fuch suit heavily modded/modernised, slammed narrowed beam custom paint, interior etc, cosmics suit mild custom mods here and there as they are less extreme due to the near standard size, but personal opinion is the fuch look better, would detailing the fuchs with a little cream be a bit much?
done a little mock up for you to see with black inserts i can email you a higher res image if you like so you can see what it looks like a bit bigger?