Yes. Absolutely.
In fact, this is how I prefer to do it. That was you can make sure there are no odd/crazy issues with your lower.
Blows my mind the folks that will submit a stripped lower... having never fired a round through it.
Sure.. chances are it'll be fine... but why take the chance when you're putting $200 and months of your life waiting on the line.
Make/buy it as a pistol... shoot it... submit it... then add the stock when approved. That's how I've done every SBR I have!