From what I gather through buying it online it still seems that you choose on the forms what it will be built into.
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It doesn't seem to matter. Before it's built into a non-banned configuration it is the receiver of a banned rifle which is banned. I don't think you'll find an FFL in the state that will accept one and transfer to you with the promise you'll build it into a non-banned item.
For the record, I think we should be able to get stripped lowers under the current law. The responsibility to build into a non-banned item should fall on us. I view it as similar to when I bought a 14.5" barrel. There were warnings on the website, and the responsibility was mine to be careful not to make it into a rifle before I got the flash hider pinned. I just don't think any FFLs are willing (and I don't blame them) to make the argument that what they'd be transferring isn't the receiver of a banned rifle, but the receiver of an HBAR or pistol because that's what the buyer said he was going to make with it.
There are several threads discussing this to the nth degree.