Are firearms legal to purchase in that configuration in the state?
You are rarely going to find a step by step list of what you can and cannot do in any state's laws.
The law is not supposed to tell you what you can do, rather if it's not outlawed then you can do it.
If your state has restrictions by feature, and specifically restricts firearms with those features, then it is likely that creating a firearm with such features is subject to the same restrictions.
