How about a straight pull bolt action AK?
My thinking is something along that line. One piece of tubing for the receiver. Bolt in trunnion so that if you wanted to change calibers just unscrew and swap in different trunnion and barrel. Tubing extends past trunnion for handguard/bipod mount with some type of dust shield. Bolt handle on left side so not to break grip cycling. Heavy or bull barrel. Trigger pack that is in a module. Stock pivots or removed to allow bolt and maybe trigger pack to be removed from the rear of the reciever. Not much left of an AK except the trunnion, bolt, and the carrier.