I've been thinking hard about this, but don't know if I can justify another tax stamp just to lost 2.5" of barrel down from the 16". If I were to do it I was thinking of a 10.5", but that really renders the round pretty useless. Would probably get better performance out of a 300BLK at that point, and the 300BLK would be smaller and lighter. Of course 300 ammo is much more expensive than 308 ammo.
From what I've found from looking online for components.
CMMG MK3 RKM11 11" handguard - LINK
CMMG MK3 12.5" barrel - LINK
it is out of stock now, but I've gotten 2 stock notifications so they come in stock pretty frequently.
The CMMG MK3 is all LR308 compatible and the rail would need to be used with a DPMS/LR308 high profile upper.
But for the price I've been throwing around buying one of the new Palmetto State Armory PA10's.
Complete Lower - LINK
Complete Upper - LINK
Total - $688 for entire gun then just have the barrel chopped down for $50
Only thing I don't like about the PA10 is the parts are different than other LR308. Some parts are compatible, but some parts PSA changed for some reason.