[Boatanchors] [BoatAnchors] 3-400Z 900 watt amp - 1960's Handbook?

[Wilson]

Nice job, but a little crowded for my taste.  
Much like an HT-45 Loudenboomer.
Cooling of the tube pins is important and may be a little lacking, but Eimacs are tough.
I’m a little concerned about bringing the filament center tap out for control.
The tube isn’t biased off, so there could potentially be some HV across the “key” contacts.
Did you ever put your hand across the key of your cathode keyed novice rig?
With that in mind, I’d consider putting the keying relay (one with good insulation), in the amp enclosure.
If you’ll be using a modern xcvr with it, you’ll want to use a transistor to control the keying relay, so maybe that can be in the amp box too.
Wilson
W4BOH