If I can find a FFL who would do the transfer of a Post Healy lower - it sounds like I can keep it as such, however that goes against HER interpretation. It does not violate any other law.
Although if I decide to build it up - it must be FA10'ed...
At which time they will discover it is Post Healy.
When you eFA10 a registration you do not need to enter where or when you acquired the item. When you register it, they have no idea when you acquired it. Lots of people are registering pre 7/16 lowers as they build them into firearms. You would be lost in a sea of legal registrations. Unless you gave them a reason to suspect you.
I've got a couple of aluminum gas blocks that aren't drilled that I had made up for me to use on .22 conversions. I think I got them from CMMG about 10 years ago. They would work fine as a way to make s bolt action AR.