Maxon OD808
For the CL use the RED channel, amp BOOST in, EDGE in, Gain control pointing at the red LED.
I would definitely second, or third, the opinion of the global master up at 2:00 and channel masters set for actual volume levels.
Not only is the tone better, you ensure that there is not any fizz to the gain as the poweramp is well represented with this approach.
For tubes, Stick with the chinese flavored tubes. I don't go for the Sovtek WB's in V1.
Not a fan of that tone but the C9 works wonders there and gives VHT's that great feel that I've come to love more than anything else. Just incredibly accurate definition. I cant describe it any other way.
A EH 12AX7 for the phase inverter with keep the attack quick and efficient. That's the only place I might experiment.
I've had 6 VHT heads over the years and have a few still and they're definitely the best Ive ever used.
The 100CL W/ Graphic is my favorite high gain head. Never had a head that was better for ME and I've had just about every single high gain head there is.
To the Cabs:The Fatbottom P50 cabs really do need to take a beating before they sound right. I never liked that about them, they should treat the suspension or cone in a way that speeds that process up. Out of the box they sound absolutely horrid. I run a looper on the clean channel, mids full up and the amp loud and I leave to ride around for a while so I dont have to hear the racket!

After a couple hours, they sound much better. The fizz disappears.
I actually think that a V30 loaded cab sounds pretty damn good with these heads even though I've heard the VHT crew say no.
I love Fatbottom cabs but for the CL I've found my V30 loaded MESA traditional sounds a bit better for what I want to hear with that head and the EL-34 poweramp.
The Ultralead is a little different story.