...have complete A1 Upper Assemblies, with forward assist and A1 flash hider, in stock?

Check with CMMG.  You may have to call them.  I know they have A1 uppers, 20" A1-style barrels in 1:12 and 1:7 twist and A1 handguards.

They are who come to mind first.

I believe Fulton Armory may also make one.

I've never bought anything from CMMG, but I've noticed previously when surfing their site that their uppers could be spec'd out with A1 receivers.  I wonder what they look like.

Quoted: I've never bought anything from CMMG, but I've noticed previously when surfing their site that their uppers could be spec'd out with A1 receivers.  I wonder what they look like.

I am 99.9% sure they are C7 uppers with the brass deflector if that matters

The easieste way to get one is buy a surplus M16A1 upper on the EE for about $200.

Del-Ton also offers complete uppers with the A1 (actually a C7 with the case deflector) upper.  I used their 16" lightweight rifle kit to build by XM177E2 clone.  You can custom order specifics (upper, barrel, FH, etc., etc.) on all of their uppers.  My experience with them was great.  For instance, the A1/C7 upper comes standard with a round forward assist.  The  teardrop was not offered as an option, but I simply emailed them and got the teardrop FA with no problems and no extra charge.  Their customer service was fantastic.

ETA: I just checked and it doesn't seem that they offer an A1 stock option.