https://www.bikecalc.com/gear_inches
yeah, 64 gear inches is where I start for road-ish riding. I think my current gear is 62 GI, which is a little low but I ride this bike off-road quite a bit. my mountain bike is 46 GI as I find that 45-50 GI works well for technical trails.
https://www.bikecalc.com/gear_inches will give you a pretty good idea of what gear-inches are possible on your tire size and gear combination.