The car is off at the cage builder right now, so I can't snap pics. TBH, you don't really need to drill that hole anyways, it's just what I did because it was expedient at the time to stop thinking and just do something
You can always run the cable the way travis did, up through the rubber grommet that carries a bunch of ECU wiring through the upper corner there near the battery tray / AC blower. Or if you're doing an all-out race car conversion and killing the AC anyways, there are multiple leftover AC-related holes to reuse.
I ended up unrelocating my battery at the end of the day. What's far simpler than relocating any battery is to put a ultra-super-light battery in the stock location. This 3.5lb battery works fine on our car:
Batteries - Ballistic Performance Components , and you can buy them from several places if you google around. The downside is ~$200+, and it's very risky to drain them (basically, you risk ruining the expensive battery permanently if you let residual drain take it below 8V, which isn't hard to do if anything's running without the engine). But honestly, that's worth not doing the battery relocate work, and this battery weighs about as much as the wiring and circuit protection for a relocate job, much less the (larger) relocated battery itself.
Another interesting option is this thing:
https://www.pegasusautoracing.com/pr...sp?RecID=10410
It's 8.4 lbs, same internals as my tiny battery (but even more capacity than mine, and mine starts the engine fine), and they've built the battery manager into the unit so that it can't be killed by draining and always charges optimally. If you're more concerned about draining and battery ruin, it might be worth the 5lbs extra weight and $600 more to have a battery that will really last and doesn't have to be babied, but is still light enough that it makes sense to retain the stock location.