What new tubes for Cary SLI-80 and where to get?

Purchased a used Cary SLI-80 recently and would like to replace all the tubes. May not be able to get them all at once due to cost so what do you recommend I replace first, second etc.

Do all the tubes other than the 6550 output tubes last much longer than the output ones? If so, then I'm guessing it's probably a good idea to replace those first? I've heard on this forum that SLI-80 owners have had good success with EH KT-88s. From a couple tube sites I've visited, they say that JJ Tesla KT-88s are good. Anyone try that one in a SLI-80?

What are good places to purchase tubes? I saw some mention of Vintage Tube Services. Called the number on their website but it's disconnected. Are they no longer in business? Anyone buy from http://www.boiaudioworks.com/ ? Prices look good there.
Upscale Audio----talk to Kevin
I don't own the SLI-80, but I recently went through what you are about to undertake. I blew a factory supplied EL34 on my amp and was forced to start doing research. I recommend doing enough research to get a clear idea of how different tube brands tend to sound. There is a concensus among tube owners, for example, that EH has a leaner sound than Svetlana. Also, what others define as "good success" might mean reliability or lack of microphonics, not necessarily the best sound. There is a ton of good tube info out there. Three good places to start are The Tube Store, TubeDepot, and audioasylum. You will discover links on all these sites that contain reliable info. Also, guitar sites I've found often have "tube shootouts" in which various brand sounds are compared. But I have to ask: Why are you interested in replacing the stock tubes?
Bojack, want replacement tubes because I'm not the original owner and thus don't know how much time have been put on the tubes. Replacing all the tubes gives me peace of mind, knowing when the tubes were first used. Also this gives me an extra set in case one goes bad. Wouldn't want to have a flat tire on the road without a spare analogy.

I'd like to try out different tubes from the stock ones to see what difference in sound I get. If I like the originals, I guess the new ones I buy will become spares.

I have a Cary SlI-80 and have used both the EH KT88 and the JJ KT88 tubes. Both are very nice with great mids and bass. The EH seemed to me a little brighter in the treble then the JJs.

I preferred the JJs for their overall balance. If your room or amps are soft in the high end you may like the EH's more.

good listening

Thanks for the info Larry. Guys, is the 6550/KT88 expected to last half as long as the 6922, 6SN7 and 5U4?