You're right about that, Paws.
When I'm financing one, it's MY adventure.
When it's a customer's nickel, that's HIS adventure.
Don't like to roll the dice on the customer's nickel until it's something I've tried and been happy with already.
Nothing's free, especially confidence in how an 'adventure' will turn out.
Oh and Jay, I keep some 330 uF filters on hand that fit that board. Should be plenty for two '250s, or one 4CX800. The holes will also accept a 6-Amp rectifier in place of the 3-Amp type we use for a one-tube amplifier. We use it mounted on three ceramic pillars for the Black Cat JB-2000, as well. It was designed for multiple "custom" applications, as either a bridge or FW doubler. Let me know when you narrow down your specs a bit further. I'm especially curious to hear how the 4CX800/GU74b works out. Still don't have any first-hand experience with that one. Got a couple of the tubes, and sockets but that's all so far, except for a couple of (still) half-defrosted ideas. Can't even call them half-baked yet. Pretty sure the right place to start is to build a "gettering" fixture bring old ceramic tubes up slowly.
73