[Coley]

If you work on and adjust the carb before redoing your timing....you will be doing all your carb adjustments over again.
This will be due to the increased idle speed, vaccuum, etc.
Hence the general tune-up rule or 'circle', timing before carb

Regardless, 6° is ok and the truck will run there, but most of these trucks started at an 8° advance and most guys bump them up to get better performance, response, etc...highly recommended as a first step.

my two bits.
Coley