On our 65 f 66 I ran 10 gauge wire from solenoid in trunk under door sill under heater box out fire wall at floor to solenoid “block” at original solenoid position on firewall.
Run 1 gauge cable from solenoid in trunk through trunk floor along frame rail to starter.
Have global west subframe connectors, so strapped cable to sub frame connector. This cable is only engerized when cranking engine over. Run a thermo sock over last two feet of cable over header pipe.
Also ran 1 gauge cable through trunk to stud welded to frame rail for additional ground.
The plastic dipped clamps are still available but I used stainless screws to attach them instead of rivets.
They didn't shoot a photo of the battery ground. I just step drilled a grommet hole behind the battery where the negative terminal is and routed it to an available threaded hole in the rear frame rail near where the battery is.
This isn't my battery but I used these terminals. They are military spec dual connection covered battery terminals.
65 2+2, 331, C4 presently apart for complete a restore
1979 Ford F150 custom, 302, C4, AC, tilt wheel, main transportation
In my old 67 coupe I relocated the battery to the trunk...but I just ran the cable under the sill plate through the interior. That being said...these days I think a better option is to use a Dynabatt( https://www.summitracing.com/parts/d...SABEgIOQfD_BwE ) and leave it up front. The reason I say that is because by the time you get done running the cable to the trunk...you have actually added weight to the car, maybe only 7lbs...but still, you come out with slightly better weight distribution at the cost of overall weight...which is where the Dynabatt shines...I have used them in several cars...they weigh very little and can be mounted in any position while taking up little space...and you don't get the voltage/amperage drop from remote mounting a battery...they are somewhat more expensive than a conventional battery though.