Need help with broken engine mount repair

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Hey guys, new to the forum, need some help.  Removing an engine I snapped a bolt, need advice on the best way to effect a repair.  The stud is housed inside a bracket that is spot and tack welded to the frame.  Appears to be some form of hardened steel.  I broke off about the last inch, and it essentially sheared where the nut cinches up on the bottom of the cradle.  It's a metric bolt, major diameter and OD thread diameter are pictured in mm, including a little rust.  This is 1 of 6, the other 5 are all intact.So what's the best, strongest way to repair this???  This is the front driver mount, so it will see tensile load as the engine twists in the unibody.  FWIW, this is on a ~1000hp Nissan R35 GTR.I have an everlast 250ex TIG/Stick welder and all the ancillaries that go along with it (argon purge gas, several different welding rods, several different electrodes, etc).  This is home hobbyist work, so I have basic tools, nothing advanced or expensive.Weld nut and threaded rod?  Weld bolt head?  Fillet weld threaded rod?  Buy another mount, cut the large diameter and bevel, fill?  Buy another mount cut and fusion weld?]
Reply:I make no claims of anything but i'd personally cut and bevel at the thick point and do the same to a new one and connect them together.  (id only do this on my own car though)Last edited by EvilBunny; 06-06-2016 at 11:43 PM.
Reply:My approach would be to cut the threads off where it starts to widen.  I would find an extra long appropriately sized bolt, one long enough that it had a section with threads and one without.  I would cut the head of the bolt off,  and trim the remaining piece to the original size that was cut off,  with one end having the majority of thread the other side about 3/8  non-threaded.   I would grind a small bevel all around on both.  I would Tig weld all the way around.   I would check for fit on the mount.   After that I would notch a V a little more than half way thru where you just welded  and re-weld.   Then I would go to the opposite side and do the same.   If you do it correctly it is essentially now one piece.  Hope this helps.
Reply:Thanks, I was leaning towards bevel for strength and penetration without putting too much heat into it.  Any advice on grade of bolt and filler material?  I assume the hardness of the bolt will decrease once the heat from the weld anneals the metal to it's base state.