Sounds like this:
Can someone point me in the direction of a simple F1 racing car design? Something that has a lot of horse power (gain). I'd like to start with a lawnmower.

Sorry chum but your request a bit fanciful. If you want to build these things you have to crawl
before you can walk let alone run with the best.

I've been at this DIY game for a long time and I've only just started to understand enough to design and build a really good amp.
I urge you to build a kit first to get you started, preferably something small. It's painting by numbers
but gets you used to how it goes together before you embark on a serious DIY project that will take years to perfect.
The chances of pulling off a fist time wonder are next to zilch.

Meantime lots of research and reading.

Just because an amp has a valve does not automatically mean it's going to be good.

If you want an easier way to go I'd test drive some pedals before you waste years learning Valves
only to find there is little benefit.
Some of the AMT pedals do a fantastic job of producing the metal sounds you desire and that will
work out faster and cheaper.
Phil.