In that era, a Winchester Model 70 Standard Grade sold for around $125.00. The J.C. Higgins FN Mauser types were no more, generally a little less. There is NO WAY Sears ever sold a rifle for $600.00 in the 1950's!
Nor do they sell for that today.....as good as they are they fetch about $350 or so today.
I've added a M-70 style safety to mine and will send it to you for $450 if you want it.