Charles, we also need to know what the application is for...?
Is this on a drag car or a dirt track car?
If a dirt car, and you are going to use a 2:1 quick steer, 12:1 box is fine, that makes it 6:1 steering.
On a drag car, the 12:1 might be ok...?
You also need to make sure which input shaft you have... a 3/4" or a 13/16" shaft...!
Don't make a mistake like I did and buy a high dollar box and find out it is the wrong shaft. If you need a 13/16" shaft I will sell you a really nice 12:1 Sweet box cheap, cheap, cheap... I cannot use it on my dirt modified steering system.