Suspension fork on beach cruiser?

[happycheapskate]

I wanna put a rockshox 30 sliver tk on my old schwinn landmark beach cruiser but the bike has a quil stem and I don't know if a quil stem will work on a mountain bike fork so I think I have to buy a thread less headset and some new bars in order for the fork to work on my bike

Buy a new bike then. It’s not worth it to fool around with converting threaded fork frames to threadless unless it’s a high end road bike. Use what it already has.