Free: Contests & Raffles.
Bare minimum go with any of the aforementioned stocks with pillars, but as stated, full aluminum is best and simplest. Will save time and sometimes a headache of bedding it yourself. Better yet, if you are looking to improve the accuracy, a good trigger job should be in order. As M70 triggers are simple to adjust, take it to a competent gunsmith and have him adjust it to a good hunting weight of 3-4 #'s. make sure the barrel is floated in that new stock, and you are of and running on your first "customized" rifle! Keep us here posted on the progress and the end result!
How much length will a Limbsaver add? I think I'm as far as I want to go with the wife on the factory stock.