As a general rule it's best to locate penetrations in areas least likely to reach a high heat level. The worst zone is centered behind the fuel pump, accessory case, etc, where fuel and oil sources congregate. In flight, flame will follow strong cooling air movement, mostly down toward the exit. Static, on the ground, it rises toward the top of the cowl. So, the best place? Outboard, near the lower corners.
A tubular fitting pumped full of FireBarrier 2000+ or a similar intumescent sealant is the gold standard, because the sealant expands to keep the space filled as other joint components (wire insulation, for example) burn or melt away. Nothing new here; it's the standard for fire protection in architecture. One of these days I'll get around to some live burn comparisons of tubular penetrations filled with FireBarrier vs tubular with sheet silicone and/or firesleeve wrap.
I have tubular penetrations available, in multiple diameters, as single tube or multi-tube on the same baseplate. Singles are cheap, $19 each.
I'm thinking of adding a wiring harness to install pressure transducers and thermocouples around the engine to more easily diagnose potential future airflow/cooling problems after first flight.
God bless the engineers
Clay, way back I installed a terminal block so I could easily repurpose the wires through the firewall, and a few miniature pressure ports. Have fun!