First of all. We need to know if the truck is a 6 or 12 volt system. 12 volt systems get by using smaller gauge wire. As to your question on using larger gauge wire than orginial...go for it as it will help you on 'line loss' or voltage drop on long wire lengths.
16 ga. is fine for all instrument gauges except amp meter. I like to use 10ga. on headlights, others might use 12 ga., 16 ga. for tail light, brake light, etc.
