NOS tube alternatives for Herron VTSP 3A r02

Looking for advice from actual Herron preamp owners who have experimented with different tubes. Recently acquired Herron  VTSP 3A r02 to be used with CAT JL5 amp. Speakers are Dynaudio C4s & ATC SCM19v2s.

I´m fully aware that manufacturer advises against tube rolling citing preamp was voiced with especially screened & selected modern tubes but I´ve decided to disregard for the following reasons:

Unit was purchased used & came with new tubes that are not originally from Herron & IM(not so humble)O & experience current production Russian and Chinese are vastly inferior in tone & timbre to NOS Telefunkens, Siemens and Amperex in relation to 6922 variants.


I do not own the VTSP but I do own the Herron VTPH-2A pre and experimented with some pricey NOS tubes. Quickly came to the realization I much prefer the new production vacuum tubes Keith provides. With that said, my favorite 6922 is the amperex 7308 and I'd bet it will sound damn good. You might save yourself some coin by going with Keith's recommendation? 
Thanks for your input jmolsberg .
Coinincidentally it is precisley the Dutch  E188CC / 7308 Amperex I´m most incinled to try. Will most likely contact Herron for a set of theirs and compare. Should Herrons prove superior can always  use the NOS in other components.
Since there are 6 of them in the VTSP I´m wondering if I´ll need a matched sextet or 1 matched quartet + 1 matched pair or 3 matched pairs.
Keith told me he goes through something like 10 tubes that don't make the cut for each one he uses. This is after having selected the best tube type. This is just comparing the same tubes for quality and matching. He told me he has a barrel full of rejects. Which people are always asking to buy, because even some of his rejects are better than 95% of what they would otherwise get just rolling the dice on the market.

Which come to think of it, is what it should be called. Not tube rolling. Rolling the dice.

Or just buy tubes from Keith. 

(The more you talk to Keith the more amazed you are at what a stone bargain his stuff is. As if the sound alone wasn't enough...)
Do what Keith says and tweak something else in your system if you need to scratch that itch.
Buy the "NOS" and the Herron set, as you outlined above, and listen and compare. It'll be fun and it's what you need to do.