BAT VK5i power tubes.. 6l6? 5881? kt66? by who?

Need help yet again... looking to replace/add to my currrent stock of Tung sol 5881 (NOS, NOT RE-ISSUES), i RECENTLY OPTED FOR the 'reissueed Tung sol 5881... fair price I guess compared to the NOS version... but two things come to mind...
1. Just how long do these tubes take to open up? ...under low to moderate power they produce little above the mid range... add power and they open up more, though not what i'm used to with the NOS versions... they've got about 100 hrs. or less right now...

2 Is it true that RCA & GE 5881's were made by Tung Sol? how can you tell?

I run a complete set of PQ USA AMPEREX WHITES W/SHEILD in the sig set... a pair of Amperex 7308 whites in the shunts... and I just bought another pair of the PQ USA 7308'S about a week or so ago... they opened up pretty quick... I don't think the 're-issued tung sol's 5881" have as yet... or they are bad. also one of the re tugns has a dent in the top of the tube... is that OK?

OTHER'S HAVE MENTIONED that 6L6, KT66, and some other tubes work the same as 5881's.... but I do not know myself... especially in the BAT vk5....

Any help is more than appreciated.... what's the best choice in the output tube slots for a bAT vk5i?