I just got off the phone with Stockade Gun Stocks. They're located in NE. They "can" install an Accu-Trigger on older Savage/Stevens rifles. It does require machining the receiver, but it's not a big deal.
Kevin Rayhill, one of the principles, said that he does it all the time. It takes 20mins and costs $50 + shipping. This price includes the Accu-Trigger.
Give them a shout! 308-432-5114 www.stockadegunstocks.com