Converting a KHS FLITE 223 into a freewheel fixie? I have this KHS Road bike that I got back in high school and was wondering if I'm able to convert it into a freewheel fixie (I think that's the right term) The bike does have vertical dropouts. Would it be cheaper to convert it or just buy a new bike altogether? 
Here is a link with all the specs I haven't changed anything since I got it!
https://khsbicycles.com/bikes/flite-223-16/
Based on the photo from your link, this bike will be difficult to convert because of the dropout having no adjustment at all.

Effectively this means you will need some other way of tensioning the chain.


Eccentric bottom bracket (expensive)
Chain tensioner (looks like a derailleur) This also means you cannot use fixed gear, because the chain will go slack on the top run if you forget and try to coast.  Also means skid-braking is impossible.
Half-link chain (expensive, heavier, somewhat uglier)


Also in your shopping list will be a single-speed conversion kit, which is a single cog and a bunch of spacers to replace your rear cassette.



Its probably advisable to fit a new chain at the time of conversion, to help keep track of mileage on components.

You might choose to replace your chainrings too, but that's more for aesthetics.  Its reasonable to pick a chainring, run the bike on only that ring by locking off the front derailleur.  You might choose to remove the inner grannie chainring for weight/appearances.  Removing the middle or large chainring will probably require a different set of chainring bolts, or some washers added to make up the missing thickness.

Brakes - For other future readers, just leave them on.   I am of the opinion that two brakes are mandatory on any road bike.  And that skid braking is not an effective emergency brake.  So don't strip off your rim brakes in the pursuit of appearance.   This doesn't apply to OP because the cassette conversion kit does not remove the freehub and the bike will just coast, if you try to skid stop on a single speed.

UPSHOT  compare the sum of cost of parts, with the loss of versatility of your quite-nice road bike.  Compare that with the cost of a second bike, and make a decision yourself as to which is more suitable.

I'd recommend N+1 if you can afford it, and would only consider conversion for a bike that isn't being used.