I'm wondering how an FM9 lower would look with an Odin Works 9 billet upper, both in design and finish.  The finish on the FM9 is light grey, whereas the current Aero upper is a lot darker.  I'm not thinking of changing things just for color; a friend asked to buy my 10.5" upper, and since I have another 10.5" 9mm upper, I'm thinking of going with something a little shorter.

If anyone has an 8.5" 9mm barrel (I assume 1/2" is consumed by the receiver, making it look like an 8" 5.56 barrel, once assembled) with a Midwest Industries handguard, please advise on the handguard length that would get the muzzle near the end of the handguard.  I'm planning on using either a thread protector or A2 for 9mm.

ETA, I just read one bad review, I believe at Primary Arms, of the Odin Billet upper having some clearance problems with the Foxtrot Mike FM9 lower.  Unfortunately, there weren't any pics, but the person said he had to somehow modify the bolt release on the FM9, something I don't want to do.

Thanks in advance!