Thinking About New Tubes

[The Guitar Nerd]

I know Mesa recommends purchasing tubes from them to ensure they run in the correct operating ranges & as I understand, the amps don't have BIAS pots. I have no problem purchasing from MB but they're out of stock on, it appears, all but one variant of their 6L6 tubes & to be honest, I don't know which ones to purchase anyhow (445, 443, 442 etc). I'm wanting to retube both my Mark VII and my Multiwatt Triple Rectifier. They're also out of stock on their 12AX7's.

I know some Tube Dealers sell tube sets that are 'specifically for' particular amps, but are these really within Mesa's operating specs? I usually set BIAS myself but I'm new to Boogie & as some things are a little different, just wanna make sure I'm getting the best sound possible.

Thanks in advance for your help!