re-tubing my Mark III head

I plan on a re-tube. I was running str442 and str454. The 442's are pretty toasted, but the 454's are still strong and clear. But, after checking the Mesa site, I see the 454 is not listed as an option.. In fact, I only see str440, which is a chinese tube. Also the str430.
Anyone have any experience with the str440? Also, isn't the str454 a Svetlana?
I'd like to stick with Mesa tubes, and loved the tone of the STR454 which, to me anyway, seem very similar to my 415's.
I was also checking out the GT6L6GE and the EH6L6... The GT6L6GE looks like it might be a contender, but what range do I get for my Blue stripe mark III. The EH (sovtek?) appeals to me in price ($45 quad) but the thought of a Sovtek doesn't knock me out....
Anyway, anyone have a suggestion for me, and anyone with STR415 experience will hold serious weight with my decision.. A bold high power tube is what I'm after. I'd like to go and purchase it at my local dealer, so if the suggestion is a non-Mesa tube, please let me know the rating I need to get, ie, GT6L6GE, EH, etc.
Oh, and I'm getting Mesa pre-amp tubes to boot.
Thanks guys, your knowledge is much appreciated..
ax. 8)

I have a set of the GT 6L6GE's in my rev A Dual Rec, They sound strong and have a great brown to them when you open them up. I tried the JJ's in it and they are very different from the way they sound in my '98 two channel dual rec. Not as much bottom end as the JJ's, but they are cleaner and more focused. You'll definitely pay more for the GE's, they are well worth the cash if you don't play ultra gain stuff.