High Amp Alternator and Accessories Questions

I found there is absolutely no need to run high amp power through the bulkhead connector. If you need to, use a separate bulkhead pass through that's rated for that amp load.

I run my alternator cable to the factory relay lug on one car with less electrical demand, then a second cable continues down to the starter. On my other car I use a distribution lug to send the power where needed. I've found that Marine Grade and high end stereo electrical components and wire are of much higher quality than I can find from auto parts sources. The fused distribution blocks are very cool from places like West Marine.

Use quality relays on every high amp draw circuit. keep all high amp draw feeds out of the bulkhead connector. I also use led lights throughout the car to lower the operating temps of the light and to reduce current draw to them.

You might consider switching from a main fuses to a main circuit breaker on the alternator cable etc, as it's easy to reset them. I also run a similar size ground cables from the alternator to my main ground. I do that with the starter too. Power flows equally through both + & -.

Regarding your alternators output at idle, try and find out at what rpm they are spinning it to get that many amps, and calculate what your pulley rpm will be with the pulleys you will be using. I suspect your pulleys wont be spinning as fast as how they were driving theirs, but who knows?