JB weld is the solution to many of life's problems, but this isn't one of them.
http://www.brownells.com/.aspx/cid=1...Trigger-Guards
If I was a betting man, I would guess all the hinged floorplate Rem700s use the standard BDL Triggerguard, but you may want to call them to find out.
You may be able to find one used, from the guys who think a bolt gun needs a detachable magazine.