rifle repair
I hate to be the bearer of bad news but you will not find any type of glue that will repair that piece. The part is cast pot metal, it is possible to weld but will require a Very skilled welder.
(read this as expensive) If you are capable of some metal work you should be able to splint the broken areas with some aluminum of appropriate thickness. I would splint,drill,tap and screw and epoxy. Be aware, that you will have to relieve the stock in the splinted area. The front screw hole, I would suggest finding a longer screw and shape a washer to fit the lines as needed.
I hope this helps
Ed