I had this same quesiton not long ago. I was told sometimes on the factory bottom metal 65 might be a bit high. It could potentally crack as per a discussion I had with Mr. Roscoe. 50-55 INCH pounds should do it. YMMV With aftermarket thicker BM Badger, Surgeon ect 65 is the "standard".
Stand the rifle straight up with the screws loose before tighting to make sure the recoil lug is up against the stock before you start to tighten.