Re: monkey arms
How much do you need to extend your LOP?
If you are only talking about needing an addt'l inch or so, then the cheapest/quickest fix is to pick up one of the Limbsaver slip on pads that will give you a little added length. I think limbsaver has a fitment guide on their website that will tell you which size pad is best suited for your Savage.
Aside from that, you are probably looking at something custom whether it is a series of additional spacers/plates between the rubber buttpad and the stock, or something like a Tubb, etc. adjustable buttplate/pad that will allow you to extend your LOP by as much as 2" or so.
If you need more than that much adjustment, you may be better served looking for an aftermarket stock that you can order with a custom LOP.