What kind of temp rating should I look for when buying replacement wiring for a Subaru 2001 engine?

 

For instance, I found wiring with 75 degree C (e.g., 167 F) rating.  Once that is all encapsulated in wire loom, etc. will it be OK in the engine bay or will it melt?

Consider the engine usually runs at 190°F coolant temp.

The exhaust system can run upwards of 1,000°F and a fair amount of heat will radiate into the engine compartment from the header pipes and cats (if you have cats).

 

Not everything under the hood will reach 190°, but anything near the engine should be rated for at least that. Probably safer to go for 220-250°F.