Andrew, you need to talk to Jesse Dunfee on here, what he don't know about these stoves ain't worth knowin.  

Some have the orginal brass valve that a gas hose just pushed on and was clamped tight
 

If your going to use propane you need a fitting like above and a regulator like this. Lowes Item, 15 bucks I think

Whatever you go with, make sure you do a thorough leak test before firing it up.
 
Im in the process of restoring one of these and I found several issues. My gas manifold (the pipe the valves screw into) had to be replaced because the threaded holes for the valves had rusted a bit . Also the valve grease inside the valves was almost gone... i took me forever to find that stuff! Every hardware store in town tried to sell me faucet grease, not the same stuff.
 
Be sure to post some pics when you get one, we love pics

Lee,
 
Valve grease is a thick grease that will not dry out or break down when exposed to hydrocarbons or mild heat. The grease is what seals the valve and also lubricates it.
 
I found alot of misinformation online when I started my search for it. Even more questionable advise from local hardware stores. No hardware store or appliance parts place in Louisville, KY carries it anymore. I dont think newer gas valves need it, so there probobly isnt much demand. I did find an industrial supply company that had it, but they refused to sell it to me unless I was HVAC licensed.
 
But I did find some online. The first one was here:
 
http://www.antiquestoves.com/toac/valvec1.htm
 
Seems like it would work but I couldn't find any info about what is was made from. So I chose this one:
 
http://www.oilybits.com/lubricants/dow-corning-molykote-1102-gas-thingy-grease/p rod_174.html
 
A tube big enough for 1000's of applications and I trust Dow Corning products. Unfortunatly I could not find a USA distributor for the stuff, so I bought from this UK store. Even with shipping it was less than $20.
 
Now my valves open and close really smooth like you would expect them to.
 

Good luck Andrew,
 
Just please be carefull, especially when hooking a stove meant for NG up to Propane. If you leave the orifice sizes on the valves the same you will have WAY too much propane going to the burners... ie. you can easily get a 1 to 2 foot high flame coming off of it, no kidding. Could be disasterous if you tried to light it inside, next to some curtains, and weren't expecting it.

Go with what you feel safe with Andrew. I have never changed an orifice and used the regulator on the propane bottles. I was able to find new orifices at the Propane store here that sells Propane appliances and fills bottles. Sometimes you find a burned up one. I had to replace one on Perry's stove. So far no problem but that doesn't mean something couldn't happen. I have 6, 3 burner stoves operating in the Wheeling Feeling Chili Cook-off this week end. Or rather ones I have went over and sold. There nice handy things to have and disply. Just check it all over like Jeremy  says.