Threaded headset to ahead headset

So I currently have a threaded headset on my beater but since I want to get rid of the quill stem I think I have to swap to a non threaded headset ? , I need a new fork , headset and stem if I'm right ? and do threaded headsets come in various sizes or is it a universal size ? and how does that correlate to which non threaded headset I'd need ?
Sorry for all the questions just a bit stuck here

You can always use a threaded to threadless adapter, but I think they are almost always ugly, and won't eliminate the flaws of quill stems. But it will give you a wider choice of stems and bars. Otherwise, yes, you'll need a new headset, forks, and stem. Also depending on your choice of stem you'll possibly also need a new bar (newer stems are generally only made for oversized bars), and a shim to for the stem.

Threaded headsets did come in various sizes, but most likely your bike has a 1" one (check beforehand). Your choice of forks will be somewhat limited since most new forks are in 1.125". Best to look for NOS steel forks with uncut steerers. Then there's the problem of the headset, since most threadless ones are in 1.125" as well, so you'll have to look around a bit. SJS still has threadless 1" headsets, and you can sometimes find very nice NOS 1" Campag ones at various places (e.g. Hilary Stone), but again, they are not common. If you choice of headset does not come with an expander/star nut, you'll also need to find one of those in 1", again SJS has them. Also you'll need a stem shim to fit newer stems made for 1.125" steerers on to a 1" one. Consider it's just a beater, it might not be worth to go to all this trouble.

You may also luck out and discover that your bike has a 1.125" threaded fork, then ignore everything above since finding 1.125" threadless parts is pretty straightforward.

technically you only need a quill to ahead converter and you will be able to use it threadless. converter is fine, not sure what flaws mentioned above would it have, since its only an extension of a steerer which works with any a head stems as normal headset.

(I have been running one for quite a while on my threaded forks, the very same setup).

That's awesome man didn't know you could get a converter like that , sorted it now thanks for the mention of the converter