Got it done, a few pic's of the process. Drilled some plug weld holes either side of the bolt hole using a washer as a quick guide.
Opened the holes up to just over the 1/2" sch'd 40 pipe wall thickness that I had cut into 72mm long pieces.
Worked the pieces of pipe into the correct location & then plug welded both ends into place.
All in all took about 3hrs from start to finish, well worth the time to do a good job