Here toy go
They make mid-length 5.45 uppers, are site sponsors, and I hear they do good work for the money.
I was looking at them recently for just that.
http://www.ar15performance.com/5_45_x_39?b=1
5.45 x 39 16" Basic mid length handguard and A2 flash
399.00
––16" Recon lightweight barrel, Nitro-carburized(black) for long life and corrosion resistance
––1 in 8 " twist rifling to stabilize the 60gr mil surplus ammo
––1/2-28 threaded muzzle
––Mid-Length length gas system
––M16 carrier with properly staked carrier key
––9310 alloy super bolt
––M4 upper receiver,
––Extended Feed Ramps to aid feeding
––Mil spec charging handle
––Test fired for function
Complete BCG add $160
A2 FH from EE $10
MAGPUL BUIS set $93 from AIM
sub-Total: $663 plus shipping and other misc charges.