Here's another shot of the mocked-up engine bay with hood or fenders. The electric panel (drivers side front) is from an 06 Ford Focus. My alternator feeds it, then I use a 40 amp fuse to power the old factory panel.
My starter motor has an internal relay, but to trigger it requires a 20 amp circuit, so that is through a relay in the new power panel. I also have relays for horns, lights, etc.
Although the Focus power panel make the car "true to form", I think that an aftermarket power panel would have been far easier.