The trigger will work but not in the original JC Stock. The inletting for the original stock is completely different. Timney trigger goes right below and the JC trigger is an "offset"/two pieace affair.
Picture of the original trigger here: http://castboolits.gunloads.com/showthread.php?141935-J-C-Higgins-model-50-mauser&
Great rifle, i bought one last year and added timney trigger and a Boyd's stock. some pictures here: http://www.canadiangunnutz.com/forum/showthread.php/1132500-JC-Higgins-Model-50-dressed-by-Boyd-s-Pics-Added