Would just say be careful on JAN, it is just a military designation, not a manufacturer. Most of the VT-231's I have (Ken-rad, Raytheon, Sylvania) ruggedized for Joint-Army-Navy spec are pretty neutral. Then the RCA VT-231's: very warm (and my favorites).
That said, I don't really see the point in rolling octals into this amp (unless you have a bunch and very few novals).
Yep The RCA ones are on the warmer side of the spectrum while the Ken-Rad, CBS (not the 5692) and Sylvania ones are on the neutral/detail/fast oriented side