Another wiring question 68 c10

[68is4me]

68 c10

Ok Running a 12si alt 90amp, everything is wired correctly. Have an #8 wire from alt to distribution block on drivers side fender with all the correct splices coming off that block.

I am running air bag suspension with 40amp max draw on the compressors. Right now the compressors are drawing right off the battery with a #4 wire. The compressor will run while the engine is not running with key on and this is how I want to keep it.

The problem with the engine running and the compressor running the fusible link from the pass junction block to the battery gets very warm. It has not been any problems yet but might be in the future.

So the question is can I upgrade the wire coming off the driver side junction block, going over to the pass block with an #8 wire and also upgrade the fusible link to a #12? Would this have any affect on the amp gauge?