Kimber Montana 1-9" 223 punched 233AI,unless you wish to build from the ground up and in that case a 700 based 1-8" N barreled 223AI at 21" gets the nod,replete with McMillan stock.

I'd be gunning the 75A-max at 3100fps+ via '335 and modest Leupie glass with ele turret ala Duplex via 1" tube. Park the A/O and pass the LRF.