Yeah, they still end up leaking, It's really not an issue in my location. I just removed the orginal wire taps off of my trailer brakes on the axle from 1998. They were still working, I needed to drop the axle.
I want to mount the coils across the edge of the firewall where the red line is. ECU will be inside the tub on the back side of the firewall extension where the yellow square is. There's 15"-18" between where the ecu and the coils. I'm more concerned with interference from the coils messing with the ecu. I've been told it doesn't matter with GM ECU's.
Was rereading this thread since it's become wiring time for my pile.
I did change up where the coils got mounted. They're up above the valve covers now. So away from the heat of the dog house and up higher than if they were mounted on the valve covers, which gets them away from the header heat a bit more too.
Back on the grounding front.
I'm using two batteries. One for the engine and one for the chassis.
I would assume the best way to achieve a good separated setup would be to use a star point on the engine with the engine grounds coming to one spot on a head and a single ground cable running to the engine battery? On the chassis side, just using the chassis as the ground with a ground cable from the other "chassis" battery to the frame?