Tube rolling my preamp with 6922EH


I'm planning on testing the Electro-Harmonix 6922EH's in my preamp, from the stock Sovtek's. Anyone have experience with these or the 6922EHG with Gold Pins? How much improvement can you get with the gold pins?
parapatton
I'm out of the ball park for expensive rare NOS. Would like to keep under a few hundred dollars for all (3) tubes.
Newbee, please tell me more about the Old Yugo's and why you like them so much. What time periods/years were the ones you like manufactured? How would you describe their sound qualities? What weaknesses, if any?
These sites have some good info: ( https://www.tubeworld.com/6922.htm ) (http://www.audiotubes.com/6dj8.htm) (http://home.att.net/~chimeraone/6dj8sound.html) Looks like the tubeworld URL might have to be copied and pasted for some reason.
One of the best bargains in NOS 6922s are Tungsrams from

www dot zeitmann-tubes dot com/

I bought from these fellows many times back when they sold on Ebay. They were trustworthy and thir testing was reliable compared with results on my tester. If I needed more tubes from the 6922 family, I'd buy from them again.
Newbie to tube rolling. The posts here gave a lot of info and food for thought. 

Thanks to All
NOS 6922 Amperex US made White label. My favorite.
  One option available now is the current production Russian  Gold Lion 6922.  Easy, accessible, match able,  reliable and warm leaning sonics.