Thanks a lot for your input, Ben.

I think I'll stick to a known C-profile. I'm just too afraid that I might hate the asymmetrical shape.
I played a couple of guitars at the local stores here (sadly there was no asymmetrical shape available) and I'm shooting for a fat Gibson-style feel this time. The fat 50's necks felt fine after a short while of playing. I think those are C-shaped aswell.
So I'll try something like .850" with a fast 0.100" taper or so. Or even a 0.120" taper.
Should be close to the current production Les Paul Standard 50's style profile, just a bit thinner.