Front shocks are no longer available from most places as Koni don't make them anymore. However, some people have had luck trying online stores in random countries like greece etc..

As for the ride. If you're going to drop it -50mm it will be bumpy and crashy regardless. That sort of ride height will also throw your geometry out the window without all of the correct adjustable parts.

Cobra springs offer excellent ride quality, but in my case they didnt offer the ride height quoted. Their -30mm srpings were actually only about a 10-15mm drop.

I ended up buying some "kilen" -30mm springs just to check the ride height (as they were so cheap) and ended up finding them just as good as the cobra's when it came to ride quality.