Looking to put together a 458 socom to replace my 45/70. For the last few years I have been using a 45/70 for timber elk hunting. Has worked great, taken a couple nice bulls. Only problem I have with the marlin 45/70 guide gun is it is heavy. Hope to drop a couple pounds by going to the ar platform. What I'm wanting is a 16 inch barrel, good break, short free floating hand guard. The lower I'm going to start with is a bushmaster. I'll need to change out the rear stock, and clean up the trigger a little. Scope I'll use will be a Leopold or red field 2.5-8x36 or the 2-7x33 that I already have. I'll be reloading. Bullet I'll try will be the 300 gr partition, 350 gr hornady interlock, or the 405 gr woodleighs. Looking for that 1600-1800 fps out the muzzle. Anyone know of a good complete upper for sale near Vancouver wa?