[Dominik]

You shouldn't even need 250Amp after the starter Maybe 50, depending on what you fuse.

I wired all my Cobras loosely according to a VW Bus from the 60s. Mainly because the wiring diagram was free on the web. I do advocate taking load off the ignition switch, via a relay for the starter.

I also kept the fans separate by feeding them directly from battery (fused), via relays. I activate by hand (switch to ground), but one might forget. A temp switch, in parallel, is good backup.

My last cars had a mechanical fuel pump, pre-historic points distributor and no wipers.
KISS, keep it simple, sexy.