Main power ground

I have made up the pictured relay panel which will sit in the front passenger foot well of my Mazda 929. I have a 6B&S gauge wire coming directly from the battery through a 70am breaker to the fuse assembly.

The relay marked switch takes a feed from ignition on at the key which initiates all the other relays for their marked components, other than the fuel pump which gets a signal from the ecu.

Now I have just watched the power grounding section in the wiring fundamentals and it has confused me a bit. I had planned on having a short earth lead go directly go to the body just near the fuse/relay assembly however I now think this would be incorrect.

Q1: Should I now be considering running the same 6B&S wire back directly to the negative side of the battery to compliment the power feed that has come from the battery or could I go to the engine block which is a much shorter run?

Hello in the perfect world running ground back to the battery would be great but I think you will be fine with it going to either the block or good clean chassis earth point. as long as you have a good earth to both the engine block and chassis

Agree, chassis ground all good. Very good tutorial from Haltech on youtube regarding this, check it out.