Modern 300B tubes: How to test?

Hope some tube guru out there could help. There are now many high power variants of 300B, like 32B, 325B, 300BXSL, etc.

How should these tubes be tested with traditional tube tester such as Heathkit TV-21 or Knight 600? What would be the "good", "new", "replace" values?

Thanks in advance for the help.