I think any kind of even rough metric that is “Amount of alcohol ==> BAC” is not very useful at all. If you want a usable average try finding some sort of an average “Amount of alcohol/pound of body weight ==> BAC” table.
That’s not quite right. You’re comparing mass and volume. 1% would be 10,000 micrograms per gram, not mL. You need to factor in for the density of blood.
Edit: Thinking about it though, it would be really close since blood is mostly water and the density of water is 1 g/mL. So depending on how accurate it needs to be, I guess this might work.