Tbone1964 sells volt gauge conversions in the parts forum.
https://67-72chevytrucks.com/vboard/...ght=volt+guage
As mentioned bigger wire never causes a problem except for less flexible and taking more space. BTW #10 wire = 30 amps. Many think that stranded wire is better for DC current. It is the opposite. Better for AC, difference is really marginal. Fine stranded wire is more flexible so it is better suited for automotive applications.