2C34 triode homebrew amp.

[pamphonica]

The other thing you'll need when you "tackle 813s" is a lot of personal insulation and great care. The HT on 813s is >2KV so it's a definite killer. I helped a (late) friend with his 400W HF 2x813 linear amp project and it was a frighteningly dangerous experience. I pointed out that he had easy access to the full 2.5KV (at 0.5A) if his hand slipped from the tuning controls. His idea of subsequent safety precautions was to rest a glass chopping board roughly over the worst bits. I stayed on the other side of the room when he was operating it!
PS His demise had nothing to do with electric shock, by the way.