Tube amp for my car

[lnx64]

As how much power is required, I have a 140 amp alternator, and my engine idles roughly at 900rpm. It idles like that because it's a 350 chevy small block with a 400 crank in it, making it a 383, along with it's cam profile.

So even at idle, im sure I can get some power in the electrical system that should be useful for something.

But using these simpler designs are interesting too.