I've been really happy with the results I've had bypassing various caps with the K72 KKaps. I always use them in the opposite direction from the writing on the case. I've never tried them the other way around (that I know of ha ha) but there was a thread from a while back on DIY Tube asylum where the OP took one apart.
Regarding the shipping, the time varies from a week to a month depending entirely on seller. No matter how long it takes, I've always gotten my order. The only semi-bad experience I've had with ex Soviet bloc sellers is that I once received a pair of tubes (6c33) that were not the ones in the ad's picture. That was a long time ago and I've learned to always ask the seller about something that needs to be that exact. The ones that don't know/care won't answer.
I usually try and buy "lots" of any KK's that I'm interested in. I try to buy 20 of whatever the cap is and buy some of different voltage ratings too. Most of the times, the shipping isn't outrageous but hey, every penny counts and there's nothing like having a few around to start burning in the moment the thought of using a particular size crosses my muddled mind.