Found it !!

[RHR]

so in keeping with your comments so far on maintaining the FSB the I should go something like the top picture as opposed to the bottom one?

I like the bottom one.

[JohnnyC]

FWIW I have a couple pistol lowers I keep around specifically so I can purchase extra parts while waiting for SBR paperwork to come back. I've never heard a definitive answer on whether or not it's kosher to have just one SBR'd lower and several short uppers along with non-NFA lowers so I figure it's cheap insurance just in case the ATF decides to interpret something.

[Fireglock]

I definitely like the lower one.