Well, I see these "upgraded' SK's with nylon bushings installed to eliminate the squeak, greasable fittings in the end caps on the goalposts, etc...I even saw one that one retrofitted a plate to, to make it more stable.
I've seen those online too....problem with those, they are no longer a true speed king any longer....once you modify the design, like adding a floor plate, you have changed the feel. The other mods are "fixes" to well worn out pedals, ones that are usually beyond normal repair methods and realy should be just thrown away. You can find mint condition original pedals once in a while (I just found a MINT WFL speed king a few weeks before christmas) but my money is on buying a new one. Its cheaper in the long run. Unless, you get detailed pics of every common problem area on a used one, and know what to look for and avoid, its basically Russian Roulette. (or Forrest Gump....used speed kings are like a box of chocolates, you never know what you're gonna get.)
The new ones feel EXACTLY the same as mint condition originals, and for what some people are asking for the used ones on Ebay, it may actually be cheaper to buy a brand new one. Plus the new ones have improved pivot points too.....nylon bushings in certain areas to eliminate the squeek. Anyone who tells you that they can tell the difference between a mint 60's/70's pedal and a brand new one as far as feel, is totally full of it! I have both and they play exactly the same! Ludwig willeven tell you that other than the nylon bushings and the black paint, there is no other difference.....they make them exactly the same way they always have! People will try you that they made different "profile" rocker cams for them, but that is bumk. They look different from the new ones because the old ones are WORN OUT. DOH
Ok, I'm off the Soap Box
Just buy a new one if you don't feel like playing the vintage speed king lottery game. :D